Processes for preparing lithium carbonate

ABSTRACT

There are provided methods for preparing lithium carbonate. For example, such methods can comprise reacting an aqueous composition comprising lithium hydroxide with CO2 by sparging the CO2 the said composition, thereby obtaining a precipitate comprising the lithium carbonate. The methods can also comprise inserting at least a portion of the precipitate into a clarifier and obtaining a supernatant comprising lithium bicarbonate and a solid comprising the lithium carbonate, separating the solid from the supernatant; and heating the supernatant at a desired temperature so as to at least partially convert the lithium bicarbonate into lithium carbonate.

The present application is a continuation of U.S. patent applicationSer. No. 14/404,466 filed on Nov. 27, 2014, that is a 35 USC 371national stage entry of PCT/CA2013/000526 filed on May 30, 2013 andwhich claims priority on U.S. 61/653,035 filed on May 30, 2012 and U.S.61/767,328 filed on Feb. 21, 2013. These documents are herebyincorporated by reference in their entirety.

The present disclosure relates to improvements in the field of chemistryapplied to the manufacture of lithium carbonate. For example, suchprocesses are useful for preparing lithium carbonate fromlithium-containing materials. For example, the disclosure also relatesto the production of other lithium products such as lithium hydroxideand lithium sulphate.

The demand for lithium carbonate is growing rapidly. The market forlithium carbonate is expanding and the current world production capacitywill likely not meet the expected increase in demand. For example,lithium carbonate is used as an additive in aluminum molten saltelectrolysis and in enamels and glasses. Lithium carbonate can also beused to control manic depression, in the production of electronic gradecrystals of lithium niobate, tantalate and fluoride as well as in theemerging technology of lithium batteries.

Lithium batteries have become the battery of choice in several existingand proposed new applications due to their high energy density to weightratio, as well as their relatively long useful life when compared toother types of batteries. Lithium batteries are used for severalapplications such as laptop computers, cell phones, medical devices andimplants (for example cardiac pacemakers). Lithium batteries are also aninteresting option in the development of new automobiles, e.g., hybridand electric vehicles, which are both environmentally friendly and“green” because of the reduced emissions and decreased reliance onhydrocarbon fuels.

High purity can be required for lithium carbonate that is used, forexample, for various battery applications. There is a limited number oflithium carbonate producers. As a direct result of increased demand forlithium products, battery manufacturers are looking for additional andreliable sources of high quality lithium products, for example lithiumcarbonate.

Few methods have been proposed so far for preparing lithium carbonate.Lithium carbonate can be prepared, for example by usinglithium-containing brines or using sea water. Some proposed methodsinvolve several purifying steps of the produced lithium carbonate. Forexample, methods have been proposed that require precipitation withsodium carbonate and involve several purifying steps of the producedlithium carbonate.

There is thus a need for providing an alternative to the existingsolutions for preparing lithium carbonate.

According to one aspect, there is provided a process for preparinglithium carbonate, the process comprising:

-   -   reacting an aqueous composition comprising lithium hydroxide        with CO₂ by sparging the CO₂ into the composition, the sparging        being carried out at a pH of about 10 to about 12.5, thereby        obtaining a precipitate comprising the lithium carbonate;    -   inserting at least a portion of the precipitate into a clarifier        and obtaining a supernatant comprising lithium bicarbonate and a        solid comprising the lithium carbonate, separating the solid        from the supernatant; and    -   heating the supernatant at a temperature of at least about        85° C. so as to at least partially convert the lithium        bicarbonate into lithium carbonate.

According to another aspect, there is provided a process for preparinglithium carbonate, the process comprising:

-   -   submitting an aqueous composition comprising a lithium compound        to an electrodialysis or electrolysis under conditions suitable        for converting at least a portion of the lithium compound into        lithium hydroxide, wherein during the electrodialysis or        electrolysis, the aqueous composition comprising the lithium        compound is at least substantially maintained at a pH having a        value of about 9.5 to about 12.5; and    -   converting the lithium hydroxide into lithium carbonate.

According to another aspect, there is provided a process for preparinglithium carbonate, the process comprising:

-   -   submitting an aqueous composition comprising a lithium compound        to an electrodialysis or electrolysis under conditions suitable        for converting at least a portion of the lithium compound into        lithium hydroxide, wherein during the electrodialysis or        electrolysis, the aqueous composition comprising the lithium        compound has a pH of greater than 7; and    -   converting the lithium hydroxide into lithium carbonate.

According to another aspect, there is provided a process for preparinglithium carbonate, the process comprising

-   -   leaching an acid roasted lithium-containing material with water        so as to obtain an aqueous composition comprising Li⁺ and at        least one metal ion;    -   reacting the aqueous composition comprising Li⁺ and the at least        one metal ion with a base so as to obtain a pH of about 4.5 to        about 6.5 and thereby at least partially precipitating the at        least one metal ion under the form of at least one hydroxide so        as to obtain a precipitate comprising the at least one hydroxide        and an aqueous composition comprising Li⁺ and having a reduced        content of the at least one metal ion, and separating the        aqueous composition from the precipitate;    -   optionally reacting the aqueous composition comprising Li⁺ and        having the reduced content of the at least one metal ion with        another base so as to obtain a pH of about 9.5 to about 11.5,        and with optionally at least one metal carbonate, thereby at        least partially precipitating at least one metal ion optionally        under the form of at least one carbonate so as to obtain a        precipitate optionally comprising the at least one carbonate and        an aqueous composition comprising Li⁺ and having a reduced        content of the at least one metal ion, and separating the        aqueous composition from the precipitate;    -   contacting the aqueous composition comprising Li⁺ and having a        reduced content of the at least one metal ion with an ion        exchange resin so as to at least partially remove at least one        metal ion from the composition, thereby obtaining an aqueous        composition comprising a lithium compound;    -   submitting the aqueous composition comprising the lithium        compound to an electrodialysis or electrolysis under conditions        suitable for converting at least a portion of the lithium        compound into lithium hydroxide; and    -   converting the lithium hydroxide into lithium carbonate.

According to another aspect, there is provided a process for preparinglithium carbonate, the process comprising

-   -   leaching a base-baked lithium-containing material with water so        as to obtain an aqueous composition comprising Li⁺ and at least        one metal ion;    -   reacting the aqueous composition comprising Li⁺ and the at least        one metal ion with a base so as to obtain a pH of about 4.5 to        about 6.5 and thereby at least partially precipitating the at        least one metal ion under the form of at least one hydroxide so        as to obtain a precipitate comprising the at least one hydroxide        and an aqueous composition comprising Li⁺ and having a reduced        content of the at least one metal ion, and separating the        aqueous composition from the precipitate;    -   optionally reacting the aqueous composition comprising Li⁺ and        having the reduced content of the at least one metal ion with        another base so as to obtain a pH of about 9.5 to about 11.5,        and with optionally at least one metal carbonate, thereby at        least partially precipitating at least one metal ion optionally        under the form of at least one carbonate so as to obtain a        precipitate optionally comprising the at least one carbonate and        an aqueous composition comprising Li⁺ and having a reduced        content of the at least one metal ion, and separating the        aqueous composition from the precipitate;    -   contacting the aqueous composition comprising Li⁺ and having a        reduced content of the at least one metal ion with an ion        exchange resin so as to at least partially remove at least one        metal ion from the composition, thereby obtaining an aqueous        composition comprising a lithium compound;    -   submitting the aqueous composition comprising the lithium        compound to an electrodialysis or electrolysis under conditions        suitable for converting at least a portion of the lithium        compound into lithium hydroxide; and    -   converting the lithium hydroxide into lithium carbonate.

According to another aspect, there is provided a process for preparinglithium carbonate, the process comprising

-   -   leaching a base-baked lithium-containing material with water so        as to obtain an aqueous composition comprising Li⁺ and at least        one metal ion;    -   optionally reacting the aqueous composition comprising Li⁺ and        the at least one metal ion with a base so as to obtain a pH of        about 4.5 to about 6.5;    -   at least partially precipitating the at least one metal ion        under the form of at least one hydroxide so as to obtain a        precipitate comprising the at least one hydroxide and an aqueous        composition comprising Li⁺ and having a reduced content of the        at least one metal ion, and separating the aqueous composition        from the precipitate;    -   optionally reacting the aqueous composition comprising Li⁺ and        having the reduced content of the at least one metal ion with        another base so as to obtain a pH of about 9.5 to about 11.5,        and with optionally at least one metal carbonate, thereby at        least partially precipitating at least one metal ion optionally        under the form of at least one carbonate so as to obtain a        precipitate optionally comprising the at least one carbonate and        an aqueous composition comprising Li⁺ and having a reduced        content of the at least one metal ion, and separating the        aqueous composition from the precipitate;    -   contacting the aqueous composition comprising Li⁺ and having a        reduced content of the at least one metal ion with an ion        exchange resin so as to at least partially remove at least one        metal ion from the composition, thereby obtaining an aqueous        composition comprising a lithium compound;    -   submitting the aqueous composition comprising the lithium        compound to an electrodialysis or electrolysis under conditions        suitable for converting at least a portion of the lithium        compound into lithium hydroxide; and    -   converting the lithium hydroxide into lithium carbonate.

According to another aspect, there is provided a process for preparinglithium carbonate, the process comprising:

-   -   submitting an aqueous composition comprising lithium sulphate to        an electrodialysis or electrolysis under conditions suitable for        converting at least a portion of the lithium sulphate into        lithium hydroxide, wherein during the electrodialysis or        electrolysis, the aqueous composition comprising lithium        sulphate is at least substantially maintained at a pH having a        value of about 9.5 to about 12.5; and    -   converting the lithium hydroxide into lithium carbonate.

According to another aspect, there is provided a process for preparinglithium carbonate, the process comprising:

-   -   submitting an aqueous composition comprising lithium sulphate to        an electrodialysis or electrolysis under conditions suitable for        converting at least a portion of the lithium sulphate into        lithium hydroxide, wherein during the electrodialysis or        electrolysis, the aqueous composition comprising lithium        sulphate has a pH of greater than 7; and    -   converting the lithium hydroxide into lithium carbonate.

According to another aspect, there is provided a process for preparinglithium hydroxide, the process comprising:

-   -   submitting an aqueous composition comprising a lithium compound        to an electrodialysis or electrolysis under conditions suitable        for converting at least a portion of the lithium compound into        lithium hydroxide.

According to another aspect, there is provided a process for preparinglithium hydroxide, the process comprising:

-   -   submitting an aqueous composition comprising a lithium compound        to an electrodialysis or electrolysis under conditions suitable        for converting at least a portion of the lithium compound into        lithium hydroxide, wherein during the electrodialysis or        electrolysis, the aqueous composition comprising the lithium        compound is at least substantially maintained at a pH having a        value of about 9.5 to about 12.5.

According to another aspect, there is provided a process for preparinglithium hydroxide, the process comprising:

-   -   submitting an aqueous composition comprising lithium sulphate to        an electrodialysis or electrolysis under conditions suitable for        converting at least a portion of the lithium sulphate into        lithium hydroxide, wherein during the electrodialysis or        electrolysis, the aqueous composition comprising lithium        sulphate is at least substantially maintained at a pH having a        value of about 9.5 to about 12.5.

According to another aspect, there is provided a process for preparinglithium hydroxide, the process comprising:

-   -   submitting an aqueous composition comprising a lithium compound        to an electrodialysis or electrolysis under conditions suitable        for converting at least a portion of the lithium compound into        lithium hydroxide, wherein during the electrodialysis or        electrolysis, the aqueous composition comprising the lithium        compound has a pH of greater than 7.

According to another aspect, there is provided a process for preparinglithium hydroxide, the process comprising:

-   -   submitting an aqueous composition comprising lithium sulphate to        an electrodialysis or electrolysis under conditions suitable for        converting at least a portion of the lithium sulphate into        lithium hydroxide, wherein during the electrodialysis or        electrolysis, the aqueous composition comprising lithium        sulphate has a pH of greater than 7.

According to another aspect, there is provided a process for preparinglithium hydroxide, the process comprising:

-   -   leaching an acid roasted lithium-containing material with water        so as to obtain an aqueous composition comprising Li⁺ and at        least one metal ion;    -   reacting the aqueous composition comprising Li⁺ and the at least        one metal ion with a base so as to obtain a pH of about 4.5 to        about 6.5 and thereby at least partially precipitating the at        least one metal ion under the form of at least one hydroxide so        as to obtain a precipitate comprising the at least one hydroxide        and an aqueous composition comprising Li⁺ and having a reduced        content of the at least one metal ion, and separating the        aqueous composition from the precipitate;    -   contacting the aqueous composition comprising Li⁺ and having a        reduced content of the at least one metal ion with an ion        exchange resin so as to at least partially remove at least one        metal ion from the composition, thereby obtaining an aqueous        composition comprising a lithium compound; and    -   submitting the aqueous composition comprising the lithium        compound to an electrodialysis or electrolysis under conditions        suitable for converting at least a portion of the lithium        compound into lithium hydroxide.

According to another aspect, there is provided a process for preparinglithium hydroxide, the process comprising:

-   -   leaching a base-baked lithium-containing material with water so        as to obtain an aqueous composition comprising Li⁺ and at least        one metal ion;    -   reacting the aqueous composition comprising Li⁺ and the at least        one metal ion with a base so as to obtain a pH of about 4.5 to        about 6.5 and thereby at least partially precipitating the at        least one metal ion under the form of at least one hydroxide so        as to obtain a precipitate comprising the at least one hydroxide        and an aqueous composition comprising Li⁺ and having a reduced        content of the at least one metal ion, and separating the        aqueous composition from the precipitate;    -   optionally reacting the aqueous composition comprising Li⁺ and        having the reduced content of the at least one metal ion with        another base so as to obtain a pH of about 9.5 to about 11.5,        and with optionally at least one metal carbonate, thereby at        least partially precipitating at least one metal ion optionally        under the form of at least one carbonate so as to obtain a        precipitate optionally comprising the at least one carbonate and        an aqueous composition comprising Li⁺ and having a reduced        content of the at least one metal ion, and separating the        aqueous composition from the precipitate;    -   contacting the aqueous composition comprising Li⁺ and having a        reduced content of the at least one metal ion with an ion        exchange resin so as to at least partially remove at least one        metal ion from the composition, thereby obtaining an aqueous        composition comprising a lithium compound; and    -   submitting the aqueous composition comprising the lithium        compound to an electrodialysis or electrolysis under conditions        suitable for converting at least a portion of the lithium        compound into lithium hydroxide.

According to another aspect, there is provided a process for preparinglithium hydroxide, the process comprising:

-   -   leaching a base-baked lithium-containing material with water so        as to obtain an aqueous composition comprising Li⁺ and at least        one metal ion;    -   optionally reacting the aqueous composition comprising Li⁺ and        the at least one metal ion with a base so as to obtain a pH of        about 4.5 to about 6.5    -   at least partially precipitating the at least one metal ion        under the form of at least one hydroxide so as to obtain a        precipitate comprising the at least one hydroxide and an aqueous        composition comprising Li⁺ and having a reduced content of the        at least one metal ion, and separating the aqueous composition        from the precipitate;    -   optionally reacting the aqueous composition comprising Li⁺ and        having the reduced content of the at least one metal ion with        another base so as to obtain a pH of about 9.5 to about 11.5,        and with optionally at least one metal carbonate, thereby at        least partially precipitating at least one metal ion optionally        under the form of at least one carbonate so as to obtain a        precipitate optionally comprising the at least one carbonate and        an aqueous composition comprising Li⁺ and having a reduced        content of the at least one metal ion, and separating the        aqueous composition from the precipitate;    -   contacting the aqueous composition comprising Li⁺ and having a        reduced content of the at least one metal ion with an ion        exchange resin so as to at least partially remove at least one        metal ion from the composition, thereby obtaining an aqueous        composition comprising a lithium compound; and    -   submitting the aqueous composition comprising the lithium        compound to an electrodialysis or electrolysis under conditions        suitable for converting at least a portion of the lithium        compound into lithium hydroxide.

According to another aspect, there is provided a process for preparinglithium hydroxide, the process comprising:

-   -   leaching an acid roasted lithium-containing material with water        so as to obtain an aqueous composition comprising Li⁺ and at        least one metal ion;    -   reacting the aqueous composition comprising Li⁺ and the at least        one metal ion with a base so as to obtain a pH of about 4.5 to        about 6.5 and thereby at least partially precipitating the at        least one metal ion under the form of at least one hydroxide so        as to obtain a precipitate comprising the at least one hydroxide        and an aqueous composition comprising Li⁺ and having a reduced        content of the at least one metal ion, and separating the        aqueous composition from the precipitate;    -   optionally reacting the aqueous composition comprising Li⁺ and        having the reduced content of the at least one metal ion with        another base so as to obtain a pH of about 9.5 to about 11.5,        and with optionally at least one metal carbonate, thereby at        least partially precipitating at least one metal ion optionally        under the form of at least one carbonate so as to obtain a        precipitate optionally comprising the at least one carbonate and        an aqueous composition comprising Li⁺ and having a reduced        content of the at least one metal ion, and separating the        aqueous composition from the precipitate;    -   contacting the aqueous composition comprising Li⁺ and having a        reduced content of the at least one metal ion with an ion        exchange resin so as to at least partially remove at least one        metal ion from the composition, thereby obtaining an aqueous        composition comprising a lithium compound; and    -   submitting the aqueous composition comprising the lithium        compound to an electrodialysis or electrolysis under conditions        suitable for converting at least a portion of the lithium        compound into lithium hydroxide.

According to another aspect, there is provided a process for preparinglithium sulphate, the process comprising:

-   -   leaching an acid roasted lithium-containing material with water        so as to obtain an aqueous composition comprising Li⁺ and at        least one metal ion, wherein the lithium-containing material is        a material that has been previously reacted with H₂SO₄;    -   reacting the aqueous composition comprising Li⁺ and the at least        one metal ion with a base so as to obtain a pH of about 4.5 to        about 6.5 and thereby at least partially precipitating the at        least one metal ion under the form of at least one hydroxide so        as to obtain a precipitate comprising the at least one hydroxide        and an aqueous composition comprising Li⁺ and having a reduced        content of the at least one metal ion, and separating the        aqueous composition from the precipitate; and    -   contacting the aqueous composition comprising Li⁺ and having a        reduced content of the at least one metal ion with an        ion-exchange resin so as to at least partially remove at least        one metal ion from the composition, thereby obtaining an aqueous        composition comprising a lithium sulphate.

According to another aspect, there is provided a process for preparinglithium sulphate, the process comprising:

-   -   leaching an acid roasted lithium-containing material with water        so as to obtain an aqueous composition comprising Li⁺ and at        least one metal ion, wherein the lithium-containing material is        a material that has been previously reacted with H₂SO₄;    -   reacting the aqueous composition comprising Li⁺ and the at least        one metal ion with a base so as to obtain a pH of about 4.5 to        about 6.5 and thereby at least partially precipitating the at        least one metal ion under the form of at least one hydroxide so        as to obtain a precipitate comprising the at least one hydroxide        and an aqueous composition comprising Li⁺ and having a reduced        content of the at least one metal ion, and separating the        aqueous composition from the precipitate;    -   optionally reacting the aqueous composition comprising Li⁺ and        having the reduced content of the at least one metal ion with        another base so as to obtain a pH of about 9.5 to about 11.5 and        with at least one metal carbonate thereby at least partially        precipitating at least one metal ion under the form of at least        one carbonate so as to obtain a precipitate comprising the at        least one carbonate and an aqueous composition comprising Li⁺        and having a reduced content of the at least one metal ion, and        separating the aqueous composition from the precipitate; and    -   contacting the aqueous composition comprising Li⁺ and having a        reduced content of the at least one metal ion with an        ion-exchange resin so as to at least partially remove at least        one metal ion from the composition, thereby obtaining an aqueous        composition comprising a lithium sulphate.

According to another aspect, there is provided a for preparing lithiumcarbonate, the process comprising:

-   -   leaching a base-baked lithium-containing material with water so        as to obtain an aqueous composition comprising Li⁺ and at least        one metal ion;    -   reacting the aqueous composition comprising Li⁺ and the at least        one metal ion with a base so as to obtain a pH of about 4.5 to        about 6.5 and thereby at least partially precipitating the at        least one metal ion under the form of at least one hydroxide so        as to obtain a precipitate comprising the at least one hydroxide        and an aqueous composition comprising Li⁺ and having a reduced        content of the at least one metal ion, and separating the        aqueous composition from the precipitate;    -   optionally reacting the aqueous composition comprising Li⁺ and        having the reduced content of the at least one metal ion with        another base so as to obtain a pH of about 9.5 to about 11.5,        and with optionally at least one metal carbonate, thereby at        least partially precipitating at least one metal ion optionally        under the form of at least one carbonate so as to obtain a        precipitate optionally comprising the at least one carbonate and        an aqueous composition comprising Li⁺ and having a reduced        content of the at least one metal ion, and separating the        aqueous composition from the precipitate;    -   contacting the aqueous composition comprising Li⁺ and having a        reduced content of the at least one metal ion with an ion        exchange resin so as to at least partially remove at least one        metal ion from the composition, thereby obtaining an aqueous        composition comprising a lithium compound;    -   submitting the aqueous composition comprising the lithium        compound to an electrodialysis or electrolysis under conditions        suitable for converting at least a portion of the lithium        compound into lithium hydroxide; and    -   converting the lithium hydroxide into lithium carbonate;

or

-   -   leaching a base-baked lithium-containing material with water so        as to obtain an aqueous composition comprising Li⁺ and at least        one metal ion;    -   optionally reacting the aqueous composition comprising Li⁺ and        the at least one metal ion with a base so as to obtain a pH of        about 4.5 to about 6.5;    -   at least partially precipitating the at least one metal ion        under the form of at least one hydroxide so as to obtain a        precipitate comprising the at least one hydroxide and an aqueous        composition comprising Li⁺ and having a reduced content of the        at least one metal ion, and separating the aqueous composition        from the precipitate;    -   optionally reacting the aqueous composition comprising Li⁺ and        having the reduced content of the at least one metal ion with        another base so as to obtain a pH of about 9.5 to about 11.5,        and with optionally at least one metal carbonate, thereby at        least partially precipitating at least one metal ion optionally        under the form of at least one carbonate so as to obtain a        precipitate optionally comprising the at least one carbonate and        an aqueous composition comprising Li⁺ and having a reduced        content of the at least one metal ion, and separating the        aqueous composition from the precipitate;    -   contacting the aqueous composition comprising Li⁺ and having a        reduced content of the at least one metal ion with an ion        exchange resin so as to at least partially remove at least one        metal ion from the composition, thereby obtaining an aqueous        composition comprising a lithium compound;    -   submitting the aqueous composition comprising the lithium        compound to an electrodialysis or electrolysis under conditions        suitable for converting at least a portion of the lithium        compound into lithium hydroxide; and    -   converting the lithium hydroxide into lithium carbonate.

According to another aspect, there is provided a process for preparinglithium hydroxide, the process comprising:

-   -   submitting an aqueous composition comprising lithium sulphate to        an electrolysis or electrodialysis under conditions suitable for        converting at least a portion of the lithium sulphate into        lithium hydroxide, wherein during the electrolysis, the aqueous        composition comprising lithium sulphate has a pH of greater than        7.

According to another aspect, there is provided a process for preparinglithium hydroxide, the process comprising:

-   -   submitting an aqueous composition comprising a lithium compound        to an electrolysis or electrodialysis under conditions suitable        for converting at least a portion of the lithium compound into        lithium hydroxide, wherein during the electrolysis or        electrodialysis, the aqueous composition comprising lithium        sulphate has a pH of greater than 7.

In the following drawings, which represent by way of example only,various embodiments of the disclosure:

FIG. 1 is a block diagram concerning an example of a process accordingto the present disclosure;

FIG. 2 is a flow sheet diagram concerning another example of a processaccording to the present disclosure;

FIG. 3 is a plot showing lithium tenor as a function of time in anotherexample of a process according to the present disclosure;

FIG. 4 is a plot showing iron tenor as a function of time in anotherexample of a process according to the present disclosure;

FIG. 5 is a plot showing aluminum tenor as a function of time in anotherexample of a process according to the present disclosure;

FIG. 6 is a diagram showing various metals tenor as a function of timein another example of a process according to the present disclosure;

FIG. 7 is a plot showing various metals tenor as a function of time inanother example of a process according to the present disclosure;

FIG. 8 is a plot showing calcium tenor as a function of molar excess ofsodium carbonate in another example of a process according to thepresent disclosure;

FIG. 9 is a plot showing magnesium tenor as a function of molar excessof sodium carbonate in another example of a process according to thepresent disclosure;

FIG. 10 is a schematic representation of another example of a processaccording to the present disclosure. FIG. 10 describe how an ionexchange resin is used so as to at least partially remove at least onemetal ion from the composition;

FIG. 11 is a plot showing calcium tenor as a function of bed volumes inan ion exchange process in another example of a process according to thepresent disclosure;

FIG. 12 is a plot showing magnesium tenor as a function of bed volumesin an ion exchange another example of a process according to the presentdisclosure;

FIG. 13 is a plot showing calcium tenor as a function of bed volumes inan ion exchange another example of a process according to the presentdisclosure;

FIG. 14 is a plot showing magnesium tenor as a function of bed volumesin an ion exchange another example of a process according to the presentdisclosure;

FIG. 15 is a plot showing lithium tenor as a function of bed volumes inan ion exchange another example of a process according to the presentdisclosure;

FIG. 16 is a plot showing various metals tenor as a function of bedvolumes in an ion exchange another example of a process according to thepresent disclosure;

FIG. 17 is a schematic representation of an example of a membraneelectrolysis cell that can be used for carrying out an example of aprocess according to the present disclosure;

FIG. 18 is a flow sheet diagram concerning another example of a processaccording to the present disclosure;

FIG. 19 is a plot showing lithium tenor as a function of time in anotherexample of a process according to the present disclosure;

FIG. 20 is a plot showing lithium tenor as a function of time in anotherexample of a process according to the present disclosure;

FIG. 21 is a plot showing sulphate tenor as a function of time inanother example of a process according to the present disclosure;

FIG. 22 is a plot showing sulphate tenor as a function of time inanother example of a process according to the present disclosure;

FIG. 23 is a flow sheet diagram concerning another example of a processaccording to the present disclosure;

FIG. 24 is a flow sheet diagram concerning another example of a processaccording to the present disclosure;

FIG. 25 is a plot showing lithium tenor as a function of time in anotherexample of a process according to the present disclosure;

FIG. 26 is a plot showing lithium tenor as a function of time in anotherexample of a process according to the present disclosure;

FIG. 27 is a schematic representation of an example of a membraneelectrolysis cell that can be used for carrying out another example of aprocess according to the present disclosure;

FIG. 28A, FIG. 28B, FIG. 28C and FIG. 28D show plots relating to aprocess according to the present disclosure using N324/AHA membranes atabout 60° C.: FIG. 28A is a plot showing current and voltage as afunction of charge passed, FIG. 28B is a plot showing feed conductivity,current density and acid pH as a function of charge passed, FIG. 28C isa plot showing the concentration in the “acid” compartment, feed andbase of various ions as a function of charge passed and FIG. 28D is aplot showing sulfate current efficiency as a function of charge passed;

FIG. 29A, FIG. 29B, FIG. 29C, FIG. 29D, FIG. 29E, FIG. 29F and FIG. 29Gshow plots relating to a process according to the present disclosureusing N324/AHA membranes at about 60° C.: FIG. 29A is a plot showingcurrent and voltage as a function of charge passed, FIG. 29B is a plotshowing feed conductivity, voltage, feed pH and acid pH as a function ofcharge passed, FIG. 29C is a plot showing a current/voltage ramp, FIG.29D is a plot showing the concentration in the feed of various ions as afunction of charge passed, FIG. 29E is a plot showing the concentrationof ammonium and sulfate in the acid compartment (or anolyte compartment)as a function of charge passed, FIG. 29F is a plot showing theconcentration of various ions in the base as a function of chargepassed, and FIG. 29G is a plot showing sulfate current efficiency as afunction of charge passed;

FIG. 30A, FIG. 30B, FIG. 30C, FIG. 30D, FIG. 30E, FIG. 30F and FIG. 30Gshow plots relating to a process according to the present disclosureusing N324/AHA membranes at about 60° C.: FIG. 30A is a plot showingcurrent and voltage as a function of charge passed; FIG. 30B is a plotshowing feed conductivity, voltage, feed pH and acid pH as a function ofcharge passed, FIG. 30C is a plot showing the concentration of variousions in the feed as a function of charge passed, FIG. 30D is a plotshowing the concentration of various ions in the base as a function ofcharge passed, FIG. 30E is a plot showing the concentration of ammoniumand sulfate in the “acid” compartment as a function of charge passed,FIG. 30F is a plot showing sulfate current efficiency as a function ofcharge passed, and FIG. 30G is a plot showing the concentration ofvarious ions in the feed as a function of charge passed;

FIG. 31A, FIG. 31B, FIG. 31C, FIG. 31D, FIG. 31E and FIG. 31F show plotsrelating to a process according to the present disclosure using N324/AHAmembranes at about 60° C. and about 200 mA/cm²: FIG. 31A is a plotshowing current and voltage as a function of charge passed, FIG. 31B isa plot showing feed conductivity, voltage, feed pH and acid pH as sfunction of charge passed, FIG. 31C is a plot showing the concentrationof various ions in the feed as a function of charge passed, FIG. 31D isa plot showing the concentration of ammonium and sulfate in the “acid”compartment as a function of charge passed, FIG. 31E is a plot showingthe concentration of various ions in the base as a function of chargepassed, and FIG. 31F is a plot showing sulfate current efficiency as afunction of charge passed;

FIG. 32A, FIG. 32B, FIG. 32C, FIG. 32D, FIG. 32E, FIG. 32F and FIG. 32Gshow plots relating to a process according to the present disclosureusing N324/AHA membranes at about 80° C. and about 200 mA/cm²: FIG. 32Ais a plot showing current and voltage as a function of charge passed,FIG. 32B is a plot showing feed conductivity, voltage, feed pH and acidpH as a function of charge passed, FIG. 32C is a plot showing acurrent/voltage ramp, FIG. 32D is a plot showing the concentration ofvarious ions in the feed as a function of charge passed, FIG. 32E is aplot showing the concentration of ammonium and sulfate in the “acid”compartment as a function of charge passed, FIG. 32F is a plot showingthe concentration of various ions in the base as a function of chargepassed, and FIG. 32G is a plot showing sulfate current efficiency as afunction of charge passed;

FIG. 33A, FIG. 33B, FIG. 33C, FIG. 33D, FIG. 33E, FIG. 33F and FIG. 33Gshow plots relating to a process according to the present disclosureusing N324/AHA membranes at about 60° C. and about 200 mA/cm²: FIG. 33Ais a plot showing current and voltage as a function of charge passed;FIG. 33B is a plot showing the concentration of various ions in the feedas a function of charge passed, FIG. 33C is a plot showing feedconductivity, voltage, feed pH and acid pH as a function of chargepassed, FIG. 33D is a plot showing the concentration of various ions inthe feed as a function of charge passed, FIG. 33E is a plot showing theconcentration of ammonium and sulfate in the “acid” compartment as afunction of charge passed, FIG. 33F is a plot showing the concentrationof various ions in the base as a function of charge passed, and FIG. 33Gis a plot showing sulfate current efficiency as a function of chargepassed; and

FIG. 34 is a plot showing the current density, pH and conductivity as afunction of charge passed in an example of a process according to thepresent disclosure using N324/AHA membranes at about 60° C. and about200 mA/cm².

Further features and advantages will become more readily apparent fromthe following description of various embodiments as illustrated by wayof examples.

The term “suitable” as used herein means that the selection of theparticular conditions would depend on the specific manipulation oroperation to be performed, but the selection would be well within theskill of a person trained in the art. All processes described herein areto be conducted under conditions sufficient to provide the desiredproduct.

In understanding the scope of the present disclosure, the term“comprising” and its derivatives, as used herein, are intended to beopen ended terms that specify the presence of the stated features,elements, components, groups, integers, and/or steps, but do not excludethe presence of other unstated features, elements, components, groups,integers and/or steps. The foregoing also applies to words havingsimilar meanings such as the terms, “including”, “having” and theirderivatives. The term “consisting” and its derivatives, as used herein,are intended to be closed terms that specify the presence of the statedfeatures, elements, components, groups, integers, and/or steps, butexclude the presence of other unstated features, elements, components,groups, integers and/or steps. The term “consisting essentially of”, asused herein, is intended to specify the presence of the stated features,elements, components, groups, integers, and/or steps as well as thosethat do not materially affect the basic and novel characteristic(s) offeatures, elements, components, groups, integers, and/or steps.

Terms of degree such as “about” and “approximately” as used herein meana reasonable amount of deviation of the modified term such that the endresult is not significantly changed. These terms of degree should beconstrued as including a deviation of at least ±5% or at least ±10% ofthe modified term if this deviation would not negate the meaning of theword it modifies.

The expression “at least one metal ion”, as used herein refers, forexample, to at least one type of ion of at least one metal. For example,the at least one metal ion can be M^(X+). In this example, M^(X+) is anion of the metal M, wherein X⁺ is a particular form or oxidation stateof the metal M. Thus, M^(X+) is at least one type of ion (oxidationstate X⁺) of at least one metal (M). For example, M^(Y+) can be anothertype of ion of the metal M, wherein X and Y are different integers.

The expression “is at least substantially maintained” as used hereinwhen referring to a value of a pH or a pH range that is maintainedduring a process of the disclosure or a portion thereof (for examplesparging, heating, electrodialysis, electrolysis, etc.) refers tomaintaining the value of the pH or the pH range at least 75, 80, 85, 90,95, 96, 97, 98 or 99% of the time during the process or the portionthereof.

The expression “is at least substantially maintained” as used hereinwhen referring to a value of a concentration or a concentration rangethat is maintained during a process of the disclosure or a portionthereof (for example sparging, heating, electrodialysis, electrolysis,etc.) refers to maintaining the value of the concentration or theconcentration range at least 75, 80, 85, 90, 95, 96, 97, 98 or 99% ofthe time during the process or the portion thereof.

The expression “is at least substantially maintained” as used hereinwhen referring to a value of a temperature or a temperature range thatis maintained during a process of the disclosure or a portion thereof(for example sparging, heating, electrodialysis, electrolysis, etc.)refers to maintaining the value of the temperature or the temperaturerange at least 75, 80, 85, 90, 95, 96, 97, 98 or 99% of the time duringthe process or the portion thereof.

The expression “is at least substantially maintained” as used hereinwhen referring to a value of an oxidation potential or an oxidationpotential range that is maintained during a process of the disclosure ora portion thereof (for example sparging, heating, electrodialysis,electrolysis, etc.) refers to maintaining the value of the oxidationpotential or the oxidation potential range at least 75, 80, 85, 90, 95,96, 97, 98 or 99% of the time during the process or the portion thereof.

The expression “is at least substantially maintained” as used hereinwhen referring to a value of an electrical current or an electricalcurrent range that is maintained during a process of the disclosure or aportion thereof (for example electrodialysis, electrolysis, etc.) refersto maintaining the value of the electrical current or the electricalcurrent range at least 75, 80, 85, 90, 95, 96, 97, 98 or 99% of the timeduring the process or the portion thereof.

The expression “is at least substantially maintained” as used hereinwhen referring to a value of a voltage or a voltage range that ismaintained during a process of the disclosure or a portion thereof (forexample electrodialysis, electrolysis, etc.) refers to maintaining thevalue of the voltage or the voltage range at least 75, 80, 85, 90, 95,96, 97, 98 or 99% of the time during the process or the portion thereof.

The below presented examples are non-limitative and are used to betterexemplify the processes of the present disclosure.

The processes of the present disclosure can be effective for treatingvarious lithium-containing materials. The lithium-containing materialcan be a lithium-containing ore, a lithium compound, or a recycledindustrial lithium-containing entity. For example, thelithium-containing ore can be, for example, α-spodumene, β-spodumene,lepidolite, pegmatite, petalite, eucryptite, amblygonite, hectorite,smectite, clays, or mixtures thereof. The lithium compound can be, forexample, LiCl, Li₂SO₄, LiHCO₃, Li₂CO₃, LiNO₃, LiC₂H₃O₂ (lithiumacetate), LiF, lithium stearate or lithium citrate. Thelithium-containing material can also be a recycled industriallithium-containing entity such as lithium batteries, other lithiumproducts or derivatives thereof.

A person skilled in the art would appreciate that various reactionparameters, will vary depending on a number of factors, such as thenature of the starting materials, their level of purity, the scale ofthe reaction as well as all the parameters since they can be dependentfrom one another, and could adjust the reaction conditions accordinglyto optimize yields.

For example, in the processes of the present disclosure useful forpreparing lithium carbonate, the processes can comprise heating thesupernatant at a temperature of at least about 85° C. so as to at leastpartially convert the lithium bicarbonate into lithium carbonate andprecipitate any dissolved lithium carbonate contained therein.

For example, in the processes of the present disclosure useful forpreparing lithium carbonate, the starting material can be, for example,lithium hydroxide. For example, it can be lithium hydroxide produced bya process as described in the present disclosure.

For example, conversion of lithium hydroxide into lithium carbonate canbe carried out by:

-   -   reacting an aqueous composition comprising the lithium hydroxide        with CO₂ by sparging the CO₂ into the composition, the sparging        being carried out at a pH of about 10 to about 12.5, thereby        obtaining a precipitate comprising the lithium carbonate;    -   inserting at least a portion of the precipitate into a clarifier        and obtaining a supernatant comprising lithium bicarbonate and a        solid comprising the lithium carbonate, separating the solid        from the supernatant; and    -   heating the supernatant at a temperature of at least about        85° C. so as to at least partially convert the lithium        bicarbonate into lithium carbonate.

The processes of the present disclosure can be effective for treatingvarious lithium-containing materials. The lithium-containing materialcan be a lithium-containing ore, a lithium compound or a recycledindustrial lithium-containing entity. For example, thelithium-containing ore can be, for example, α-spodumene, β-spodumene,lepidolite, pegmatite, petalite, eucryptite, amblygonite, hectorite,smectite, clays, or mixtures thereof. The lithium compound can be, forexample, LiCl, Li₂SO₄, LiHCO₃, Li₂CO₃, LiNO₃, LiC₂H₃O₂ (lithiumacetate), lithium stearate, lithium citrate or LiF. Thelithium-containing material can also be a recycled industriallithium-containing entity such as lithium batteries, other lithiumproducts or derivatives thereof.

A person skilled in the art would appreciate that various reactionparameters such as, for example, reaction time, reaction temperature,reaction pressure, reactant ratio, flow rate, reactant purity, currentdensity, voltage, retention time, pH, oxidation/reduction potential, bedvolumes, type of resin used, and/or recycle rates, will vary dependingon a number of factors, such as the nature of the starting materials,their level of purity, the scale of the reaction as well as all theparameters previously mentioned since they can be dependent from oneanother, and could adjust the reaction conditions accordingly tooptimize yields.

For example, when the process comprises heating the supernatant at thetemperature of at least about 85° C. so as to at least partially convertthe lithium bicarbonate into lithium carbonate, it can further compriseprecipitating any dissolved lithium carbonate contained therein.

For example, when sparging, the pH can be at least substantiallymaintained at a value of about 10 to about 12.5, about 10.5 to about12.0, about 10.5 to about 11.5, about 10.7 to about 11.3, about 10.8 toabout 11.2, about 10.9 to about 11.1 or about 11.

For example, the supernatant can be heated at a temperature of at leastabout 87° C., at least about 89° C., at least about 91° C., at leastabout 93° C., at least about 95° C., at least about 97° C., about 85° C.to about 105° C., about 90° C. to about 100° C., about 92° C. to about98° C., about 93° C. to about 97° C., about 94° C. to about 96° C., orabout 95° C.

For example, during the processes, the aqueous composition comprisinglithium hydroxide can be at least substantially maintained at aconcentration of lithium hydroxide of about 30 to about 70 g/L, about 40to about 60 g/L or about 48 to about 55 g/L.

For example, the sparging can be carried out at a temperature of about10 to about 40° C., about 15 to about 30° C. or about 20 to about 30° C.

For example, when heating the supernatant, the latter can be maintainedat a Li concentration of about 1 to about 10 g/L, about 2 to about 6 g/Lor about 3 to about 5 g/L.

For example, during the electrodialysis or the electrolysis, the pH ofthe composition comprising lithium sulfate or the lithium compound canbe at least substantially maintained at a value of about 9.5 to about12.5, about 10 to about 12, about 10.5 to about 12.5, about 11 to about12.5, about 11 to about 12, about 9.8 to about 10.8, about 9.8 to about10.2, about 10 to about 10.5, or about 10.

For example, during the electrodialysis or the electrolysis, the pH ofthe composition comprising lithium sulfate or the lithium compound canbe at least substantially maintained at a value between 7 and 14.5, 7and 14, 7 and 13.5, 7 and 13, 7 and 12, 7 and 10; or 7 and 9.

For example, the pH of the wherein during the electrodialysis orelectrolysis, the aqueous composition comprising lithium sulfate or thelithium compound can have a pH between 7 and 14.5, 7 and 14, 7 and 13.5,7 and 13, 7 and 12, 7 and 10; or 7 and 9.

For example, the pH of the wherein during the electrodialysis orelectrolysis, the aqueous composition comprising lithium sulfate or thelithium compound can have a pH of about 9.5 to about 12.5, about 10 toabout 12, about 10.5 to about 12.5, about 11 to about 12, about 9.8 toabout 10.8, about 9.8 to about 10.2, about 10 to about 10.5, or about10.

For example, the electrodialysis or the electrolysis can be carried outin a three-compartment membrane electrolysis cell.

For example, the electrodialysis or the electrolysis can be carried outin a two-compartment membrane electrolysis cell.

For example, the electrodialysis or the electrolysis can be carried outin a three-compartment membrane cell.

For example, the electrodialysis or the electrolysis can be carried outin a two-compartment membrane cell.

For example, the electrolysis can be carried out in a monopolarelectrolysis cell. For example, the electrolysis can be carried out in amonopolar three-compartment electrolysis cell.

For example, the electrolysis can be carried out in a bipolarelectrolysis cell. For example, the electrolysis can be carried out in abipolar three-compartment electrolysis cell.

For example, the electrodialysis can be carried out in a bipolarelectrodialysis cell. For example, the electrodialysis can be carriedout in a bipolar three-compartment electrodialysis cell.

For example, the aqueous composition comprising the lithium sulphate orthe lithium compound can be submitted to a monopolar membraneelectrolysis process.

For example, the aqueous composition comprising the lithium sulphate orthe lithium compound can be submitted to a monopolar three compartmentmembrane electrolysis process.

For example, the aqueous composition comprising the lithium sulphate orlithium compound can be submitted to a bipolar membrane electrodialysisprocess.

For example, the aqueous composition comprising the lithium sulphate orlithium compound can be submitted to a bipolar three compartmentelectrodialysis process.

For example, the electrodialysis or the electrolysis can be carried outin an electrolytic cell in which a cathodic compartment is separatedfrom the central or anodic compartment by a cathodic membrane.

For example, the electrodialysis can be carried out in a bipolarmembrane. For example such a membrane is a membrane that splits watermolecules (H+ and OH−) and wherein acid and base solution are produced,for example, at low concentration.

For example, the electrolysis can be carried out by using a monopolarmembrane. For example, it can be carried out by using an electrolysisstack comprising three compartment cells equipped with monopolarmembranes and bipolar electrodes. For example, such electrodes areeffective for evolving gaseous hydrogen (H₂) at the cathodic electrodeand gaseous oxygen (O₂) or chlorine gas (Cl₂) at the anodic electrode.For example, such electrodes are effective for splitting watermolecules.

For example, the membrane can be a perfluorinated membrane or astyrene/divinylbenzene membrane.

For example, the membrane can be a cation exchange membrane,PEEK-reinforced membrane.

For example, the electrodialysis or the electrolysis can be carried outby introducing the aqueous composition comprising the lithium compound(for example LiCl, LiF, Li₂SO₄, LiHCO₃, Li₂CO₃, LiNO₃, LiC₂H₃O₂ (lithiumacetate), lithium stearate or lithium citrate) into a centralcompartment, an aqueous composition comprising lithium hydroxide into acathodic compartment, and generating an aqueous composition comprisingan acid (for example HCl, H₂SO₄, HNO₃ or acetic acid) in an anodiccompartment (or acid compartment). The person skilled in the art wouldunderstand that, for example, when LiCl is introduced in the centralcompartment, HCl is generated in the anodic compartment, for example amonopolar membrane electrolysis cell. For example, when LiF is used inthe central compartment, HF is generated in the anodic compartment. Forexample, when Li₂SO₄ is used in the central compartment, H₂SO₄ isgenerated in the anodic compartment. For example, when LiHCO₃ is used inthe central compartment, H₂CO₃ is generated in the anodic compartment.For example, when LiNO₃ is used in the central compartment, HNO₃ isgenerated in the anodic compartment. For example, when LiC₂H₃O₂ is usedin the central compartment, acetic acid is generated in the anodiccompartment. For example, when lithium stearate is used in the centralcompartment, stearic acid is generated in the anodic compartment. Forexample, when lithium citrate is used in the central compartment, citricacid is generated in the anodic compartment.

For example, the electrodialysis or the electrolysis can be carried outby introducing the lithium sulphate into a central compartment, anaqueous composition comprising lithium hydroxide into a cathodiccompartment, and generating an aqueous composition comprising sulphuricacid in an anodic compartment.

For example, an anolyte used during the process can comprise ammonia,ammonium bisulfate, ammonium sulfate and/or NH₄OH. For example, ananolyte used during the process can comprise ammonia, ammoniumbisulfate, ammonium sulfate and/or NH₄OH, thereby generating an ammoniumsalt.

For example, the process can further comprise adding ammonia and/orNH₄OH, for example gaseous or liquid ammonia, for example NH₃ and/orNH₄OH, in an anolyte compartment, in an acid compartment, in theanolyte, at an anode or adjacently thereof, wherein the anode is usedfor the process.

For example, the process can further comprise adding ammonia and/orNH₄OH, in an anolyte compartment, in an anolyte at an anode oradjacently thereof, thereby generating an ammonium salt, wherein theanode is used for the process.

For example, the process can further comprise adding ammonia and/orNH₄OH in an anolyte compartment or in an anolyte used for the process.

For example, the process can further comprise adding ammonia and/orNH₄OH in an anolyte used for the process, thereby generating an ammoniumsalt.

For example, the ammonium salt can be (NH₄)₂SO₄.

For example, concentration of the produced ammonium salt can be about 1to about 4 M, about 1 to about 3 M, or about 1.5 M to about 2.5 M.

For example, concentration of the ammonium bisulfate present in theanolyte can be at a concentration of about 1 to about 4 M, about 1 toabout 3 M, or about 1.5 M to about 3.5 M.

For example, concentration of the ammonium sulfate present in theanolyte can be at a concentration of about 1 to about 4 M, about 1 toabout 3 M, or about 1.5 M to about 3.5 M.

For example, pH of the anolyte is maintained at a value of about −0.5 toabout 4.0, about −0.5 to about 3.5, about −0.25 to about 1.5 or about−0.25 to about 1.0.

For example, ammonia can be added in a substoichiometric quantity ascompared to sulfuric acid produced.

For example, ammonia can be added in a molar ratio ammonia:sulfuric acidcomprised between 0.5:1 and 2:1 or between 1:1 and 1.9:1.

For example, the electrodialysis or the electrolysis can be carried outby introducing the aqueous composition comprising the lithium compound(for example LiCl, LiF, Li₂SO₄, LiHCO₃, Li₂CO₃, LiNO₃, LiC₂H₃O₂ (lithiumacetate), lithium stearate or lithium citrate) into a centralcompartment, an aqueous composition comprising lithium hydroxide into acathodic compartment, and an aqueous composition comprising NH₃ into ananodic compartment. For example, when an aqueous composition comprisingNH₃ is introduced into the anodic compartment, proton-blocking membranesmay not be required and membranes which are capable, for example ofrunning at a temperature of about 80° C. and which may, for example,have lower resistance can be used. For example, the aqueous compositioncomprising the lithium compound can further comprise Na⁺.

For example, during the electrodialysis or the electrolysis, the aqueouscomposition comprising lithium hydroxide can be at least substantiallymaintained at a concentration of lithium hydroxide of about 30 to about90 g/L, about 40 to about 90 g/L, about 35 to about 70 g/L, about 40 toabout 66 g/L, about 45 to about 65 g/L, about 48 to about 62 g/L orabout 50 to about 60 g/L.

For example, during the electrodialysis or the electrolysis, the aqueouscomposition comprising lithium hydroxide can be at least substantiallymaintained at a concentration of lithium hydroxide of about 1 to about 5M, about 2 to about 4 M, about 2.5 to about 3.5 M, about 2.7 to about3.3 M, about 2.9 to about 3.1 M or about 3 M.

For example, during the electrodialysis or the electrolysis, the aqueouscomposition comprising sulphuric acid can be at least substantiallymaintained at a concentration of sulphuric acid of about 30 to about 100g/L, about 40 to about 100 g/L, about 60 to about 90 g/L, about 20 toabout 40 g/L, about 20 to about 50 g/L, about 25 to about 35 g/L, orabout 28 to about 32 g/L.

For example, during the electrodialysis or the electrolysis, the aqueouscomposition comprising sulphuric acid can be at least substantiallymaintained at a concentration of sulphuric acid of about 0.1 to about 5M, about 0.2 to about 3M, about 0.3 to about 2 M, about 0.3 to about 1.5M, about 0.4 to about 1.2 M, about 0.5 to about 1 M, or about 0.75 M.

For example, during the electrodialysis or the electrolysis, the aqueouscomposition comprising lithium sulphate can be at least substantiallymaintained at a concentration of lithium sulphate of about 5 to about 30g/L, about 5 to about 25 g/L, about 10 to about 20 g/L, or about 13 toabout 17 g/L.

For example, during the electrodialysis or the electrolysis, the aqueouscomposition comprising lithium sulphate can be at least substantiallymaintained at a concentration of lithium sulphate of about 0.2 to about3 M, about 0.4 to about 2.5 M, about 0.5 to about 2 M, or about 0.6 toabout 1.8 M.

For example, during the electrodialysis or the electrolysis, the aqueouscomposition comprising lithium sulphate can be at least substantiallymaintained at a concentration of sulphate (SO₄ ²⁻) of about 0.2 to about3 M, about 0.4 to about 2.5 M, about 0.5 to about 2 M, or about 0.6 toabout 1.8 M.

For example, during the electrodialysis or the electrolysis, the aqueouscomposition comprising lithium sulphate can comprise between about 1 toabout 30%, about 1 to about 25%, about 5 to about 25%, about 10 to about25%, by weight of sodium based on the total weight of sodium and lithiumin the composition.

For example, during the electrodialysis or the electrolysis, the aqueouscomposition comprising lithium sulphate can comprise sodium. The ratioLi:Na (g/g) can be about 2:1 to about 10:1 or about 3:1 to about 5:1.

For example, during the electrodialysis or the electrolysis, temperatureof the aqueous composition comprising lithium sulphate or lithiumcompound can be at least substantially maintained at a value of about 20to about 80° C., about 20 to about 60° C., about 30 to about 40° C.,about 50 to about 60° C., or about 46 to about 54° C.

For example, during the electrodialysis or the electrolysis, temperatureof the aqueous composition comprising lithium sulphate can be at leastsubstantially maintained at a value of about 20 to about 60° C., about30 to about 40° C., about 50 to about 60° C., or about 46 to about 54°C. The person skilled in the art would understand that such atemperature can vary as a function of the membrane chosen in theelectrolysis cell.

For example, when an aqueous composition comprising NH₃ is introducedinto the anodic compartment during the electrodialysis or theelectrolysis, temperature of the aqueous composition comprising lithiumsulphate can be at least substantially maintained at a value of about 20to about 100° C., about 20 to about 95° C., about 20 to about 90° C.,about 45 to about 95° C., about 65 to about 95° C., about 20 to about80° C. about 20 to about 80° C., about 75 to about 85° C., about 20 toabout 60° C., about 30 to about 40° C., about 35 to about 65° C., about40 to about 60° C., about 35 to about 45° C., about 55 to about 65° C.,about 50 to about 60° C. or about 46 to about 54° C.

For example, during the electrodialysis or the electrolysis, electricalcurrent can be at least substantially maintained at a density of about300 to about 6000 A/m², about 2000 to about 6000 A/m², about 3500 toabout 5500 A/m². about 4000 to about 5000 A/m², about 400 to about 3000A/m², about 500 to about 2500 A/m², about 1000 to about 2000 A/m² about400 to about 1200 A/m², about 400 to about 1000 A/m², about 300 to about700 A/m², about 400 to about 600 A/m², about 425 to about 575 A/m²,about 450 to about 550 A/m², or about 475 to about 525 A/m².

For example, during the electrodialysis or the electrolysis, electricalcurrent can be at least substantially maintained at a density of about30 to about 250 mA/cm², 50 to about 250 mA/cm², about 75 to about 200mA/cm² or about 100 to about 175 mA/cm².

For example, during the electrodialysis or the electrolysis, electricalcurrent can be at least substantially maintained at a constant value.

For example, during the electrodialysis or the electrolysis, voltage canbe at least substantially maintained at a constant value.

For example, during the process, voltage can be at least substantiallymaintained at a constant value that is about 3 to about 10 V or about 4to about 7 V. For example, the cell voltage can be at leastsubstantially maintained at a value of about 1.0 V to about 8.5 V, about1.0 V to about 3.0 V, about 2.0 V to about 3.0 V, about 3.0 V to about8.5 V, about 6.5 V to about 8 V, about 5.5 V to about 6.5 V or about 6V.

For example, during the electrodialysis or the electrolysis, the overallcurrent efficiency can be about 50% to about 90%, about 60% to about90%, about 60% to about 85%, about 60% to about 70%, about 60% to about80%, about 65% to about 85%, about 65% to about 80%, about 65% to about75%, about 70% to about 85% or about 70% to about 80%.

For example, during the electrodialysis or the electrolysis, the overallLiOH current efficiency can be about 50% to about 90%, about 60% toabout 90%, about 60% to about 70%, about 60% to about 80%, about 65% toabout 85%, about 65% to about 80%, about 65% to about 75%, about 70% toabout 85% or about 70% to about 80%.

For example, during the electrodialysis or the electrolysis, the overallH₂SO₄ current efficiency can be about 55% to about 95%, 55% to about90%, about 60% to about 85%, about 65% to about 80%, about 85% to about95% or about 70% to about 80%.

For example, after generation of LiOH by means of electrolysis orelectrodialysis, a mixture comprising Li2SO4 and/or LiHSO4 and H2SO4 canbe obtained. For example, Li2SO4 can at least be partially recoveredfrom said mixture by carrying out an electrodialysis.

For example, the aqueous composition comprising Li⁺ and at least onemetal ion can be reacted with the base so as to obtain a pH of about 4.8to about 6.5, about 5.0 to about 6.2, about 5.2 to about 6.0, about 5.4to about 5.8 or about 5.6.

For example, the aqueous composition comprising Li⁺ and at least onemetal ion can be reacted with lime.

For example, the at least one metal ion comprised in the aqueouscomposition that is reacted with the base so as to obtain a pH of about4.5 to about 6.5 can be chosen from Fe²⁺, Fe³⁺ and Al³⁺.

For example, the at least one metal ion comprised in the aqueouscomposition that is reacted with the base so as to obtain a pH of about4.5 to about 6.5 can comprise Fe³⁺.

For example, the at least one metal ion comprised in the aqueouscomposition that is reacted with the base so as to obtain a pH of about4.5 to about 6.5 can comprise Al³⁺.

For example, the at least one metal ion comprised in the aqueouscomposition that is reacted with the base so as to obtain a pH of about4.5 to about 6.5 can comprise Fe³⁺ and Al³⁺.

For example, the at least one hydroxide comprised in the precipitate canbe chosen from Al(OH)₃ and Fe(OH)₃.

For example, the precipitate can comprise at least two hydroxides thatare Al(OH)₃ and Fe(OH)₃.

For example, the base used so as to obtain a pH of about 4.5 to about6.5 can be lime.

For example, lime can be provided as an aqueous composition having aconcentration of about 15% by weight to about 25% by weight.

For example, the processes can further comprise maintaining the aqueouscomposition comprising Li⁺ and the at least one metal ion that isreacted with a base so as to obtain a pH of about 4.5 to about 6.5 at anoxidative potential of at least about 350 mV.

For example, the aqueous composition can be at least substantiallymaintained at an oxidative potential of at least about 350 mV bysparging therein a gas comprising O₂. For example, the gas can be air.Alternatively, the gas can be O₂.

For example, the processes can comprise reacting the aqueous compositioncomprising Li⁺ and having the reduced content of the at least one metalion with the another base so as to obtain a pH of about 9.5 to about11.5, about 10 to about 11, about 10 to about 10.5, about 9.8 to about10.2 or about 10.

For example, the base used so as to obtain a pH of about 9.5 to about11.5 can be NaOH, KOH or LiOH.

For example, the base used so as to obtain a pH of about 9.5 to about11.5 can be NaOH.

For example, the at least one metal carbonate can be chosen from Na₂CO₃,NaHCO₃, and (NH₄)₂CO₃.

For example, the base and metal carbonate can be a mixture of aqueousNaOH, NaHCO₃, LiOH and LiHCO₃.

For example, the at least one metal carbonate can be Na₂CO₃.

For example, the aqueous composition comprising Li⁺ and having thereduced content of the at least one metal ion can be reacted with theanother base over a period of time sufficient for reducing the contentof the at least one metal ion in the aqueous composition below apredetermined value. For example, the at least one metal ion can bechosen from Mg²⁺, Ca²⁺ and Mn²⁺. For example, the reaction can becarried out over a period of time sufficient for reducing the content ofCa²⁺ below about 250 mg/L, about 200 mg/L, about 150 mg/L, or about 100mg/L. For example, the reaction can be carried out over a period of timesufficient for reducing the content of Mg²⁺ below about 100 mg/L, about50 mg/L, about 25 mg/L, about 20 mg/L, about 15 mg/L or about 10 mg/L.

For example, the ion exchange resin can be a cationic resin.

For example, the ion exchange resin can be a cationic resin that issubstantially selective for divalent and/or trivalent metal ions.

For example, contacting with the ion exchange resin can allow forreducing a content of Ca²⁺ of the composition below about 10 mg/L, about5 mg/L, about 1 mg/L, or about 0.5 mg/L.

For example, contacting with the ion exchange resin can allow forreducing a content of Mg²⁺ of the composition below about 10 mg/L, about5 mg/L, about 1 mg/L, or about 0.5 mg/L.

For example, contacting with the ion exchange resin can allow forreducing total bivalent ion content such as Ca²⁺, Mg²⁺ and Mn²⁺ of thecomposition below about 10 mg/L, about 5 mg/L, about 1 mg/L or about 0.5mg/L.

For example, the acid roasted lithium-containing material can be leachedwith water so as to obtain the aqueous composition comprising Li⁺ and atleast three metal ions chosen from the following metals: iron, aluminum,manganese and magnesium.

For example, the acid roasted lithium-containing material can be leachedwith water so as to obtain the aqueous composition comprising Li⁺ and atleast three metal ions chosen from Al³⁺, Fe²⁺, Fe³⁺, Mg²⁺, Ca²⁺, Cr²⁺,Cr³⁺, Cr⁶⁺, Zn²⁺ and Mn²⁺.

For example, the acid roasted lithium-containing material can be leachedwith water so as to obtain the aqueous composition comprising Li⁺ and atleast four metal ions chosen from Al³⁺, Fe²⁺, Fe³⁺, Mg²⁺, Ca²⁺, Cr²⁺,Cr³⁺, Cr⁶⁺, Zn²⁺ and Mn²⁺.

For example, during the electrodialysis or the electrolysis, the pH canbe at least substantially maintained at a value of about 10 to about 12,about 10.5 to about 12.5, or about 11 to about 12.

For example, the acid roasted lithium-containing material can beβ-spodumene that has been previously reacted with H₂SO₄.

For example, the acid roasted lithium-containing material can beobtained by using a process as described in CA 504,477, which is herebyincorporated by reference in its entirety.

For example, the acid roasted lithium-containing material can be aα-spodumene, β-spodumene, lepidolite, pegmatite, petalite, amblygonite,hectorite, smectite, clays, or mixtures thereof, that has beenpreviously reacted with H₂SO₄.

For example, the base-baked lithium-containing material can beβ-spodumene that has been previously reacted with Na₂CO₃ and with CO₂,and eventually heated.

For example, when carrying out the leaching of the base-baked lithiummaterial, lithium carbonate can be formed in the baked ore (very lowsolubility in water). It can then be slurried and sparged with CO₂ (forexample in an autoclave) to convert lithium carbonate to water solublelithium bicarbonate, and heated at a temperature of about 85 to about95° C. to drive off CO₂ and re-precipitate a more pure lithiumcarbonate. The bicarbonate step can be repeated to obtain a higherpurity grade. It can be possible to bake the β-spodumene with sodiumhydroxide and leach out lithium hydroxide that could need purification.

In the processes of the present disclosure, the pH can thus becontrolled by further adding some base, some acid or by diluting. TheORP can be controlled as previously indicated by sparging air.

For example, when reacting the aqueous composition comprising Li⁺ andthe at least one metal ion with a base so as to obtain a pH of about 4.5to about 6.5 and thereby at least partially precipitating the at leastone metal ion under the form of at least one hydroxide so as to obtain aprecipitate, the metal of the at least one metal ion can be Fe, Al, Cr,Zn or mixtures thereof.

For example, when reacting the aqueous composition comprising Li⁺ andhaving the reduced content of the at least one metal ion with anotherbase so as to obtain a pH of about 9.5 to about 11.5, and withoptionally at least one metal carbonate, thereby at least partiallyprecipitating at least one metal ion, the metal of the at least onemetal ion can be Mn, Mg, Ca or mixtures thereof.

For example, when contacting the aqueous composition comprising Li⁺ andhaving a reduced content of the at least one metal ion with anion-exchange resin so as to at least partially remove at least one metalion, the at least one metal ion can be Mg²⁺, Ca²⁺ or a mixture thereof.

EXAMPLE 1

As shown in FIG. 1, lithium hydroxide can be obtained, for example, byusing such a process and by using a pre-leached lithium-containingmaterial as a starting material. For example, various leached ores suchas acid roasted β-spodumene can be used. The process shown in FIG. 1 canalso be used for producing lithium carbonate. According to anotherembodiment, the starting material can be a lithium compound such aslithium sulphate, lithium chloride or lithium fluoride. In such a case,the process would be shorter and would be starting at the box entitled“membrane electrolysis”.

Acid Roasted β-Spodumene (AR β-Spodumene)

Two different blends of the AR β-spodumene were tested. The samples werecomposed of different ratios of the flotation and dense media separation(DMS) concentrates. The samples were identified as 75/25 and 50/50. Theformer sample contained about 75% by weight of the flotation concentrateand about 25% by weight of the DMS concentrate. The latter samplecontained substantially equal portions by mass of the two concentrates.The assay data of the feed samples is summarized in Table 1. The twosamples had very similar analytical profiles. The 75/25 sample hadhigher levels of Fe, Mn, Mg, Ca and K than the 50/50 sample. Bothsamples had typical compositions for AR β-spodumene.

TABLE 1 Assay Data of the AR β-Spodumene Samples Li Si Al Fe Na S Sample% 75/25 Comp 2.24 25.0 10.5 1.04 0.39 6.09 50/50 Comp 2.29 24.4 10.40.96 0.36 6.06 Cr Zn Mn Mg Ca K Sample g/t 75/25 Comp 167 134 1962 11863431 3653 50/50 Comp 163 103 1755 905 2311 3376

Concentrate Leach (CL) and Primary Impurity Removal (PIR)

The objectives of the Concentrate Leach (CL) and the Primary ImpurityRemoval (PIR) were 1) to dissolve lithium sulphate contained in the ARβ-spodumene and 2) to remove the major impurities from the processsolution that co-leach with lithium from the feed solids.

A four tank cascade was used for the combined CL and PIR process circuit(see FIG. 2). The AR β-spodumene was added using a feed hopper that wasequipped with a vibratory feeder. Each of the reactors was equipped withthe following: an overhead mixer motor (0.5 hp) with a 4-blade pitchimpeller attached, pH and ORP (Oxidation Reduction Potential) probes.The PIR reactors also had air spargers located directly below theimpeller. The process slurry flowed by gravity from one reactor to thenext through overflow ports. The overflow port of the CL reactor was setsuch that the active volume of the tank was about 32 L. The PIR reactorseach had an active volume of about 14 L. The overflow from PIR Tank 3(the last reactor of the tank train) was pumped to the filtrationstation.

About 1,200 kg of the 75/25 and about 1,400 kg of the 50/50 ARβ-spodumene samples were leached in about 85 hours of operation. Thechange over from one feed to the other occurred at the 37th hour ofoperation. Time zero of the operation was when pulp began to overflowfrom the CL reactor.

In the CL step, water and solids were combined in an agitated tank at a50:50 weight ratio and mixed for about 30 to about 45 minutes underambient conditions. Lithium was extracted along with undesirable ganguemetals such as, for example, iron, aluminum, silicon, manganese, andmagnesium. The obtained slurry (CL slurry) thus comprised a solidcomposition and an aqueous (liquid) composition containing solubilizedLi⁺ (lithium ions) as well as solubilized ions of the above-mentionedmetals. The CL slurry pH and ORP were monitored but not controlled.Alternatively, the pH can eventually be controlled by further addingsome base, some acid or by diluting. The ORP can also be controlled aspreviously indicated by sparging air. The CL slurry flowed by gravity tothe PIR Tank 1. The aqueous composition can alternatively be separatedfrom the solid composition before being introduced in the PIR Tank 1. Insuch a case, the aqueous composition (instead of the whole CL slurry asit is the case for the present example) would be inserted into Tank 1.

After 9 hours of operation there was sufficient volume of the Wash 1fraction (the first displacement wash fraction generated when washingthe combined CL and PIR solids residue) to recycle back to the CL. Theinitial recycle rate of the Wash 1 was set to about 50% of the wateraddition requirement of the CL. After 37 hours of operation, this amountwas increased to make-up 60% of the water addition to the process. Thiswash stream contained on average about 12 g/L Li (about 95 g/L ofLi₂SO₄).

Primary Impurity Removal (PIR) was carried out, for example, tosubstantially remove Fe, Al and Si from the aqueous composition whilesubstantially not precipitating any lithium. In this process, the pH ofthe concentrate leach slurry (comprising the aqueous composition and thesolid composition) was elevated to about 5.6 by lime slurry addition tothe three PIR tanks. The lime was added as a slurry having aconcentration of about 20 wt %. The CL slurry was thus converted into aprecipitate and an aqueous composition. The impurities such as Fe, Aland Si were at least substantially precipitated as insoluble metalhydroxides and found in the precipitate while the lithium ions weresubstantially found in the aqueous composition. The retention time forthe PIR circuit was about 45 to about 60 minutes. Air was sparged intothe PIR tanks in order to maintain the oxidative potential of theprocess slurry at or above about 350 mV. At this level, iron present inthe ferrous (Fe²⁺) form would likely oxidize to ferric iron (Fe³⁺), aform suitable for precipitation at such a pH. Thus, a precipitatecomprising, for example, metal hydroxides of Fe, Al and Si was obtainedand eventually separated from the aqueous composition comprising lithiumions. In the PIR, the pH can thus be controlled by further adding somebase, some acid or by diluting. The ORP can be controlled as previouslyindicated by sparging air.

The resulting slurry (comprising the aqueous composition and the solidcomposition (comprising the precipitate)) was filtered on pan filters.The filtrate (aqueous composition comprising lithium ions and having areduced content of the above mentioned metals (such as Fe, Al and Si))proceeded to Secondary Impurity Removal (SIR). The PIR filter cakeunderwent three displacement washes. The first wash fraction wascollected separately from the second two washes. The first wash streamwas recycled to the CL process as a portion of the water feed stream torecover the contained lithium. Wash fractions 2 and 3 were combined andstored as a solution. This solution can be used for lime slurry make-upto recover the lithium units.

The lithium tenors in CL and PIR are presented in FIG. 3. At hour 9, thefirst wash fraction from PIR was recycled back to the CL tank to make-uphalf of the water addition to the leach. Lithium tenors increasedthroughout the circuit to about 18 g/L (about 142.6 g/L of Li₂SO₄) as aresult. At hour 37.5, the recycle rate was increased to make-up 60% ofthe water to the leach and lithium tenors increased to about 25 g/L(about 198 g/L of Li₂SO₄). The PIR first wash lithium tenors ranged fromabout 12 to about 15 g/L (about 95 g/L to about 118.8 g/L of Li₂SO₄).

The pH was substantially steady throughout the operation once thethroughput was reduced. The ORP of the slurry in PIR tank 3 wassubstantially steady and above about 350 mV during the operation. Theiron tenors for CL and PIR are presented in FIG. 4. At hours 10 and 54,the pH of PIR3 was near a value of about 5.6 and yet the iron tenor inthe PIR3 liquor increased.

Iron and aluminum profiles are presented in FIGS. 4 and 5. Both iron andaluminum showed increasing levels in the CL tank throughout the run.Iron levels maintained below about 5 mg/L in PIR3 for most of the runregardless of the increase observed in CL. Aluminum in PIR3 was lessthan about 10 mg/L for the first 40 hours, and then ranged between about20 and about 65 mg/L for the remainder of the operating time.

A mass balance for the CL and PIR circuits is shown in Table 2. Lithiumextraction and impurity precipitation is calculated based on solidsassays. The mass balance shows that overall about 82% of the lithiumpresent in the AR β-spodumene feed proceeded to Secondary ImpurityRemoval (SIR). Specifically, about 79% lithium extraction was achievedfor the 75/25 blend and about 86% for the 50/50 blend. The portions ofaluminum and iron that either did not leach or precipitated totaledabout 96% and about 99%, respectively. Other tests have demonstratedthat yields of about 95% of extraction from the AR β-spodumene can beobtained.

TABLE 2 Mass Balance of CL and PIR circuits Metal Content, mg/L or %Process Streams Quantity, Li Al Fe Cr Zn INPUTS Op Hr kg % or mg/L g/tor mg/L AR 13.5 485 2.25 106909 9792 173 130 B-Spodumene 25.5 436 2.19102675 10072 192 154 37.5 323 2.15 101087 10352 211 177 49.5 407 2.21104792 11261 212 148 61.5 435 2.28 106909 8883 212 119 73.5 363 2.31107438 8813 182 88 80.0 205 2.31 107438 8813 182 88 PIR Wash 1 13.5 11311200 77 11.2 <0.2 5.6 25.5 252 11200 77 11.2 <0.2 5.6 37.5 214 11200 7711.2 <0.2 5.6 49.5 273 15300 65 4.3 <0.2 5.9 61.5 273 15300 65 4.3 <0.25.9 73.5 249 12300 64 3.1 <0.2 3.5 80.0 157 12600 62 1.5 <0.2 3.6OUTPUTS Li Al Fe Cr Zn PIR3 Solids 13.5 536 0.60 126491 11960 247 13325.5 277 0.40 121198 11471 229 160 37.5 268 0.58 119611 13219 211 18749.5 333 0.31 123315 13079 211 164 61.5 294 0.46 126491 11051 210 14073.5 282 0.48 124374 10771 201 141 80.0 169 0.50 125962 11051 201 141PIR3 Solution 13.5 600 10700 37.3 60.5 <0.2 5.5 25.5 642 20100 6.95 1.05<0.2 3.9 37.5 470 16400 1.3 0.8 <0.2 1.7 49.5 515 24550 36.45 3.3 <0.25.4 61.5 582 23500 71 3.2 <0.2 4.6 73.5 484 22800 19.5 2.15 <0.2 3.4580.0 290 25900 65.5 3.4 <0.2 4.8 Process Streams Density Metal Units, gINPUTS Op Hr kg/L % Solids Li Al Fe Cr Zn AR 13.5 10912 51847 4749 84 63B-Spodumene 25.5 9555 44797 4394 84 67 37.5 6938 32621 3340 68 57 49.58995 42653 4583 86 60 61.5 9907 46455 3860 92 52 73.5 8397 39053 3203 6632 80.0 4732 22007 1805 37 18 PIR Wash 1 13.5 1.06 1195 8 1 0 1 25.51.07 2631 18 3 0 1 37.5 1.06 2262 15 2 0 1 49.5 1.10 3800 16 1 0 1 61.51.12 3748 16 1 0 1 73.5 1.09 2821 15 1 0 1 80.0 1.08 1829 9 0 0 1OUTPUTS Li Al Fe Cr Zn PIR3 Solids 13.5 47.2 3218 67836 6414 132 71 25.530.1 1107 33534 3174 63 44 37.5 36.3 1556 32094 3547 57 50 49.5 39.31032 41042 4353 70 54 61.5 33.6 1354 37238 3253 62 41 73.5 36.8 135335070 3037 57 40 80.0 36.8 844 21268 1866 34 24 PIR3 Solution 13.5 1.075995 21 34 0 3 25.5 1.12 11477 4 1 0 2 37.5 1.11 6970 1 0 0 1 49.5 1.1510953 16 1 0 2 61.5 1.15 11926 36 2 0 2 73.5 1.15 9580 8 1 0 1 80.0 1.166464 16 1 0 1 Units IN 13.5 12107 51855 4750 84 64 25.5 12186 44815 439784 68 37.5 9200 32636 3343 68 58 49.5 12795 42669 4585 86 62 61.5 1365546471 3861 92 53 73.5 11218 39068 3204 66 33 80.0 6560 22017 1805 37 19TOTAL 77722 279532 25945 517 356 Units OUT 13.5 9212 67857 6448 132 7425.5 12584 33538 3174 63 46 37.5 8527 32095 3547 57 51 49.5 11985 410584355 70 57 61.5 13281 37274 3255 62 44 73.5 10934 35078 3038 57 41 80.07308 21284 1867 34 25 TOTAL 73830 268184 25684 475 338 Extraction 13.571 25.5 88 37.5 78 49.5 89 61.5 86 73.5 84 80.0 82 TOTAL 82Precipitation 13.5 131 135 158 113 25.5 75 72 76 66 37.5 98 106 83 8849.5 96 95 81 90 61.5 80 84 67 80 73.5 90 95 86 124 80.0 97 103 91 132TOTAL 96 99 92 93 Accountability, OUT/IN % 76 131 136 158 117 103 75 7276 68 93 98 106 83 87 94 96 95 81 92 97 80 84 67 82 97 90 95 86 126 11197 103 91 135 TOTAL 95 96 99 92 95 *Averages if shown in italics

Secondary Impurity Removal

Secondary Impurity Removal (SIR) was performed on the PIR filtrate(aqueous composition comprising lithium ions and having a reducedcontent of the above mentioned metals (such as Fe, Al and Si)) tosubstantially precipitate and remove Ca, Mg and Mn impurities therefrom.Feed addition to the SIR circuit started at operating hour 6 (six hoursafter overflow from the CL tank). There are four process tanks arrangedin a cascade (see FIG. 2). The tank volumes could be adjusted during therun from about 11.8 to about 17.5 L by changing the tank overflow ports.All tanks are baffled and agitated by overhead mixers. pH, ORP andtemperature were monitored in all tanks.

In the first two agitated tanks, the pH was increased to about 10 usingabout 2 M sodium hydroxide (NaOH) (another base). Following this pHadjustment, an excess of sodium carbonate (Na₂CO₃) based on levels oftargeted impurities in the feed was added to the third tank to convertthe remaining divalent impurities to insoluble carbonates. The slurryfrom the third tank was pumped to a clarifier. Underflow solids wereremoved and recovered by filtration while the overflow solution wascollected in a 1000 L tote.

Averaged impurity tenors of solutions from the Concentrate Leach stagethrough to the final tank of Secondary Impurity Removal are shown inTable 3 and FIG. 6.

TABLE 3 Profile of Selected Impurities Li Al Fe Cr Zn Mn Mg Ca Streammg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/L CL 23880 1737 985 5.9 9.1 178109 468 PIR1 21290 34 9 0.0 4.3 174 153 435 PIR2 21240 28 8 0.0 4.0 173175 433 PIR3 21140 30 8 0.0 4.2 174 179 434 SIR1 20093 1 0 0.0 0.0 2 43426 SIR2 22500 0 0 0.0 0.0 1 19 352 SIR3 19050 1 0 0.0 0.0 1 16 322 SIR422400 0 0 0.0 0.0 1 14 241

Impurities introduced in the leach stage included iron, aluminum,chromium, zinc, magnesium, manganese and calcium. Substantially all ofthe chromium and over about 98% of the iron and aluminum substantiallyprecipitated in the first PIR tank (PIR1). Minimal precipitationoccurred in the next two tanks of PIR (PIR2 and PIR3). By the first tankof SIR (SIR1), the only impurities substantially remaining in solutionwere magnesium and calcium. All other elements were less than about 1mg/L. Although most of the precipitation occurred in SIR1, the extraretention time of SIR2 dropped the magnesium tenor from about 40 toabout 20 mg/L. From SIR2 through SIR4, magnesium and calcium tenorsshowed a steady decline with more retention time. Impurity levels forSIR4 averaged to about 1 mg/L Mn, about 14 mg/L Mg and about 241 mg/L Caduring the pilot plant run. However, levels as low as about 200 mg/L Caand about 2 mg/L Mg were attained by the optimization of key parameters.

pH and ORP were monitored throughout the operation. pH was onlycontrolled in the first two tanks. Initially, the selected pH for SIR2was about 10. At operating hour 30, the pH in SIR2 was increased toabout 10.5. With the exception of a 2 hour period at hour 50, where thepH in SIR2 dropped to about 10, pH remained at about 10.5 for theremainder of the run. The average pH values achieved over the twoperiods were about 10.1 and about 10.5 and the resulting sodiumhydroxide consumptions were about 0.022 and about 0.024 kg sodiumhydroxide per hour, respectively. The overall sodium hydroxideconsumption was about 10 kilograms of sodium hydroxide solution perabout 1000 kg of lithium carbonate equivalent (LCE).

The impurity tenors of SIR2 solutions are plotted over time in FIG. 7.These solutions have been pH adjusted by sodium hydroxide to above 10,but have not yet been dosed with sodium carbonate. Magnesium tenors arelower after the adjustment, but the levels show a gradual trenddownwards that appears to begin prior to the set point change. It shouldbe noted that later in the pilot plant, the retention time was increasedfor all SIR tanks, which may have also contributed to improvedprecipitation performance.

Calcium and magnesium tenors in solutions leaving SIR4 are plotted inFIGS. 8 and 9. These Figures relate impurity tenor (Mg and Ca only) withthe sodium carbonate dosage used at the time the sample was taken.Additionally, the data are plotted based on the retention times of theentire SIR circuit at the time of each sample. Within the range tested,as the sodium carbonate increased, metal tenors decreased. It should benoted that the lowest impurity tenors also corresponded with greatercircuit retention time. Sodium carbonate dosage is expressed as molarexcess of calcium impurities present prior to sodium carbonate addition(using assays from SIR2). The data indicated that the solution tenor ofCa can decrease to below about 200 mg/L.

Product from the SIR circuit was assayed every 4 hours as it left thefinal tank (SIR4) (see FIG. 2). The SIR4 product was pumped into a 100 Lclarifier and the overflow from the clarifier was filtered through a 0.5μm spiral wound cartridge filter and then collected in 1000 L plastictotes. These totes were assayed again to confirm bulk calcium feedtenors for Ion Exchange (IX). When the totes were sampled, light brownsolids were observed in the bottom of each tote. Assays revealed asignificant drop in calcium tenor from the solutions leaving the finaltank of the circuit (SIR4) to the solution sitting unmixed in the totes.A comparison of the average assays for both streams is presented inTable 4, below.

TABLE 4 Effect of Aging on SIR Product Mg Ca Stream mg/L mg/L SIR4Product 17 286 IX Feed Tote 15 140

A mass balance for the SIR circuit is shown in Table 5. The mass balanceshows that overall about 92% of the magnesium and all of the manganesereported to the solids. The distribution of lithium to the solids isabout 0.9% for an overall SIR lithium recovery of about 99.1%.

TABLE 5 Mass Balance of SIR circuit Metal Content, mg/L or % ProcessStreams Quantity, Mn Mg Ca INPUTS Op Hr kg g/t or mg/L SIR Feed 13.5 60072 69 438 25.5 642 109 111 463 37.5 470 146 209 459 49.5 515 199 216 45161.5 582 227 181 415 73.5 484 203 154 441 80.0 290 195 150 443 OUTPUTSMn Mg Ca SIR Solids Solids Pail 1 3.17 64700 63600 86300 Solids Pail 24.03 68000 54700 85200 SIR4 Solution 13.5 176 0.7 18 309 25.5 383 1.2 21358 37.5 426 1.6 48 370 49.5 395 0.1 20 325 61.5 208 0.2 7.6 191 73.5214 0.2 1.4 220 80.0 206 0.4 1.5 225 Process Streams Density MetalUnits, g INPUTS Op Hr kg/L Mn Mg Ca SIR Feed 13.5 1.08 40 38 242 25.51.03 68 69 288 37.5 1.12 62 88 193 49.5 1.14 90 97 203 61.5 1.10 121 96220 73.5 1.20 81 62 177 80.0 1.17 48 37 109 OUTPUTS Mn Mg Ca SIR SolidsSolids Pail 1 205 201 273 Solids Pail 2 274 221 343 SIR4 Solution 13.51.05 0 3 52 25.5 1.09 0 7 126 37.5 1.11 1 18 143 49.5 1.15 0 7 112 61.51.15 0 1 35 73.5 1.20 0 0 39 80.0 1.21 0 0 38 Precipitation = 13.5 10092 79 (1 − SIR4 solution/ 25.5 99 89 56 SIR Feed)*100 37.5 99 79 26 49.5100 93 45 61.5 100 99 84 73.5 100 100 78 80.0 100 99 65 TOTAL 100 92 62Accountability, OUT/IN % 94 94 81 Distribution to Solids 100 92 53 SIRLithium Recovery SIR solids, kg Li 0.3 SIR total out, kg Li 36.3 LithiumRecovery, % 99.1

Ion Exchange

The SIR product is processed through an ion-exchange (IX) circuit tofurther reduce the Ca and Mg tenors prior to lithium product production.The IX circuit comprises three columns packed with Purolite™ S950, acationic resin that can be used in the sodium form that is selectivetowards divalent and trivalent metal ions. Purolite™ S950 comprises anaminophosphonic resin supported on a macroporous cross-linked polymer.It can be used for the removal of heavy metal cations. At high pH it canbe active in the removal of Group 2 metal cations (Mg, Ca and Ba) andCd, Ni and Co. At high pH divalent metal cations are preferentiallyabsorbed over monovalent metal cations (e.g. Li, Na, K). Any ionexchange resin that would be suitable for substantially selectivelyremoving of divalent metal cations such as Ca²⁺ and Mg²⁺ and/ortrivalent metal cations could be alternatively used in the presentdisclosure. Alternatively, more than one type of resin can be used toselectively remove the various metal cations. Thus, different ionexchange resins can be used for different metal cations.

The operating philosophy used for the IX circuit was a Lead-LagRegeneration process (see FIGS. 2 and 10). Two of the IX columns of thecircuit are involved with Ca and Mg removal, while the resinregeneration cycle is conducted on the third column. A schematicillustrating the solution flow through the IX circuit and the lead-lagregeneration operation is provided in FIG. 10. The loading of Ca and Mgwill take place on two columns denoted lead and lag and will produce aneffluent having both Ca and Mg solution tenors below about 10 mg/L. Theloaded column undergoes stripping and regeneration stages prior to beingreintroduced as the lag column for the next loading cycle. The columnswere constructed from clear PVC pipe. Each column had a diameter ofabout 15 cm and a height of about 76 cm. The bed volume of each columnwas about 10 L.

The parameters for the IX operation are summarized in Table 6. Theseparameters were based on the laboratory tests results and the Lead-Lagcolumn configuration was designed to process 75 bed volumes (BV) of feedsolution before the Ca and Mg tenors in the Lag effluent exceeded theestablished upper limit that was about 10 mg/L that was established foreach cation. After processing 75 BV's of feed solution, the combinedabsorption capacity of the resin in the Lead and Lag columns would notbe sufficient to produce a final effluent with the Ca and Mg tenors eachbelow about 10 mg/L. At this point the loading cycle is complete. TheLead column is promoted to the Regeneration stage. The Lag column takesthe Lead position. The Regenerated column becomes the Lag column.

The Regeneration stage involved washing the Lead column with reverseosmosis (RO) water to flush out the Li rich solution within the column.This solution is passed to the Lag column. The Feed Wash stage isfollowed by Acid Strip using about 2 M HCl. This removes the absorbedCa, Mg, Li and other metal cations from the resin. The resin is now inthe acid form. An Acid Wash stage follows to rinse the remaining HCl(aq)from the column. The resin is then converted to the Na form by passingabout 2 M NaOH through the column (Regeneration Stage). The final stepinvolves washing the excess NaOH from the column using reverse osmosis(RO) water. The resin is now regenerated and ready to be promoted to theLag position for the next Loading cycle. The effluent from the AcidStrip cycle was collected separately. The effluents from the Acid Wash,Regeneration and Regeneration Wash cycles were all captured in the samedrum.

The Acid Strip stage produces a solution that contains Li, Ca, and Mg.The data indicated that Li elutes from the column first followed by Caand Mg. It can be possible to separately capture the Li fraction and asa result produce a lithium chloride solution.

TABLE 6 IX Pilot Operation Parameters Bed Volume IX Stage Solution (BV)Rate, BV/h Loading IX Feed 75 5 Feed Wash RO Water 1.5 5 Acid Strip 2MHCl 3 5 Acid Wash RO Water 5 5 Regeneration 2M NaOH 3 5 RegenerationWash RO Water 3 5 1 BV = 10 L

A total of about 2154 L of SIR Product solution was processed throughthe IX circuit in four cycles. The average Li, Ca, and Mg tenors of thefeed solutions for each cycle are summarized in Table 7.

TABLE 7 IX - Average Feed Solution Li, Ca and Mg Tenors IX Average FeedSolution Tenor, mg/L Cycle Li Ca Mg C1 16480 176 28.2 C2 17600 140 12.9C3 & C4 21940 78.7 3.6

A cycle was initially designed to operate the Loading stage for 75 BV's.The average loading flow rate was about 832 mL/min (about 49.9 L/h).Cycle 1 was the only cycle where 75 BVs of feed solution was passedthrough the Lead-Lag columns.

The Ca Loading curve for Cycle 1, where the Ca tenor of the effluentsfrom the Lead and Lag columns are plotted against cumulative bed volumeprocessed, is presented in FIG. 11. Also plotted on this plot is theaverage Ca tenor in the feed solution and the selected limit for Catenor in the Lag effluent (about 10 mg/L) for the present example. Thebreakthrough point for Ca of the Lead column occurred at 7.5 BV. The Catenor of the Lead effluent was about 82.3 mg/L after 75 BV's indicatingthat the loading capacity of the Lead column was not reached for Ca. Thebreakthrough point for Ca of the Lag column occurred at about 35 BV. TheCa tenor in the Lag effluent increased above about 10 mg/L between the60th and 65th BV. It was decided to continue the Loading stage of Cycle1 through to the 75th BV point even though the Lag effluent was aboveabout 10 mg/L of Ca. The effluent from the 65^(th) to 75^(th) BV pointwas diverted to a 200 L drum and kept separate from the main productsolution of Cycle 1. The diverted solution was later combined with themain Cycle 1 product when it was determined that the Ca tenor in theresulting combined solution would not exceed about 10 mg/L.

A similar loading profile for Mg for Cycle 1 is presented in FIG. 12.The average Mg tenor in the feed solution and for example an upper limitof Mg tenor in the Lag effluent (about 10 mg/L) are also included inthis plot. The breakthrough point for Mg of the Lead column occurred at7.5 BV's. After 75 BV's the Mg tenor of the Lead effluent was about 9.5mg/L. The breakthrough point for Mg of the Lag column occurred at 52.5BV's. After 75 BV's the Mg tenor of the Lag effluent was about 0.8 mg/L,well below the selected limit level for Mg in the IX product solution,according to this example.

Cycles 2 and 3 had to be stopped before 75 BV's of feed solution couldbe processed through the columns. The Ca tenors of the Lag effluent foreach IX cycle are plotted against cumulative BV in FIG. 13. In the caseof Cycle 2, the Ca breakthrough points for the Lead and Lag columnsoccurred at <about 7.5 and about 23 BV, respectively. Cycle 2 wasstopped after about 68 BV. The Ca in the Lag effluent had reached about13 mg/L at after about 60 BV's. Breakthrough of Ca for the Lag column ofCycle 3 occurred within the first 5 BV's. Cycle 3 was stopped afterabout 30 BV's. The tenor of the Ca in the Lag effluent at the 30 BVpoint was about 7.7 mg/L.

The balance of the Cycle 3 feed solution was processed over about 36.4BV's in Cycle 4. The Ca breakthrough points for the Lead and Lag columnsfor Cycle occurred at <about 7.5 and about 7.5 BV, respectively.Extrapolation of the Cycle 4 Lag effluent Ca tenor data indicated thatthe product solution would have a Ca tenor>about 10 mg/L after 60 BV's.

The Mg tenors of the Lag effluent for each IX cycle are plotted againstcumulative BV in FIG. 14. It is clear that the Mg tenor in the Lageffluent never approached a level close to the level of about 10 mg/L.

The average Li tenors of the Lead effluent for each IX cycle are plottedagainst cumulative BV in FIG. 15. Also included in this plot are theaverage Li tenors of the feed solutions. The data indicated thatsubstantially no Li loaded onto the resin.

The Li, Ca and Mg tenors in the Acid Strip effluents of Cycle 1 and 2are plotted against cumulative BV in FIG. 16. The data indicate that Liis stripped first from the resin and reaches for example an upper limittenor in the range of about 0.5 and about 1.5 BV's. The Ca and Mg elutedfrom the resin starting around 1 BV and both reach for example an upperlimit tenor at about 2 BV. The three metals are eluted from the resinafter 3 BV's. The Ca and Mg profiles for Cycle 3 and 4 were similar.

Reagent consumptions are reported relative to the LCE produced on a kgper about 1000 kg basis. The lithium sulphate stream produced from IonExchange contained about 39.1 kg of Li (this includes 100% of thelithium units in a PIR PLS sample that did not undergo SIR and IX). Theequivalent mass of lithium carbonate that could be produced given nolosses in downstream processes would equal about 187.7 kg.

The IX circuit produced about 2006 L of product solution. The assay dataof the IX Product solutions are summarized in Table 8. The Li tenorranged from about 15.7 to about 21.9 g/L. The ranges of the Ca and Mgtenors were about 2.4 to about 5.7 mg/L and <about 0.07 to about 0.2mg/L, respectively. Other constituents of note were Na and K at about3.5 g/L and about 0.1 g/L on average, respectively. The elements thatassayed below the detection limits of the analytical technique are alsolisted in Table 8.

TABLE 8 IX Product Solution Assays IX Solution Tenor, mg/L Product LiSO4 Cl Na K Ca Sr Mg Ba Carboy 1 15700 120000 5 3980 107 3.8 0.61 0.20.03 Carboy 2 16700 120000 4 1990 105 5.7 0.9 0.18 0.043 Carboy 3 21900160000 5 4470 117 2.4 0.74 <0.07 0.05 Elements Assaying below Detection(Detection Limits provided in mg/L) Ag Al As Be Bi Cd Co Cr Cu Fe <0.5 <0.8 <3 <0.002 <1 <0.3 <0.3 <0.2 <0.1 <0.2 Mn Mo Ni P Pb Sb Se Sn Ti Tl<0.04 <0.6 <1 <5    <2 <1   <3   <2   <0.1 <3   U V W Y Zn <1    <0.07<2 <0.02    <0.7

The mass balance of for the IX circuit is provided in Table 9. Goodaccountability for Li was obtained. About 2.7% of the Li was lost in theStrip/Regeneration process solution. The process removed about 97.6% ofthe Ca and about 99.0% of the Mg contained in the feed solutions.

The IX circuit met the process objectives by reducing the Ca and Mgtenors in the product solution to below about 10 mg/L for each metalcation. Further, a high quality lithium sulphate solution was produced.

TABLE 9 IX Mass Balance Assays, mg/L or % Process Stream kg or L Li CaMg SIR Feed C1 750 16480 176 28.2 SIR Feed C2 682 17600 140 12.9 SIRFeed C3 359 21940 78.7 3.6 SIR Feed C4 364 21940 78.7 3.6 IX ProductCarboy 1 914 15700 3.8 0.2 IX Product Carboy 2 478 16700 5.7 0.18 IXProduct Carboy 3 614 21900 2.4 <0.07 IX Regen Reject Drum 1 202 16.935.5 2.47 IX Regen Reject Drum 2 208 12.2 16.7 <0.07 IX Strip - Solids0.8 0.002 26.5 0.0004 IX Strip - Solution 111 8760 718 229 ElementalMasses IN, kg SIR Feed C1 12.36 0.13 0.02 SIR Feed C2 11.99 0.10 0.01SIR Feed C3 7.87 0.03 0.00 SIR Feed C4 7.99 0.03 0.00 Total IN, kg 40.20.28 0.03 Elemental Masses OUT, kg IX Product Carboy 1 14.35 0.00 0.00IX Product Carboy 2 7.99 0.00 0.00 IX Product Carboy 3 13.45 0.00 0 IXRegen Reject Drum 1 0.00 0.01 0.00 IX Regen Reject Drum 2 0.00 0.00 0 IXStrip - Solids 0.00 0.22 0.00 IX Strip - Solution 0.97 0.08 0.03 TotalOUT, kg 36.8 0.32 0.03 Distribution, % Product 97.3 2.4 1.0 Tails 2.797.6 99.0 Distribution Total 100.0 100.0 100.0 OUT/IN, % 91.4 112.4 80.3Li Loss, % 2.7 M Removed, % 97.6 99.0

Examination of the semi-quantitative x-ray diffraction (SQ-XRD) data ofcomposite samples of the CL/PIR residues showed that each samplecontains both α- and β-spodumene. The SQ-XRD data for the CL/PIRresidues generated from each of the two feed samples (75/25 and 50/50)are summarized in Table 10. The presence of α-spodumene indicates thatthe phase transition step that was conducted by a third party vendor(acid roast of α-spodumene) was not 100% efficient. Any Li present inthis form would thus not be chemically available to thehydrometallurgical process. It should be noted that the efficiency ofthe phase transition step (conversion from α-spodumene to β-spodumene)is not 100% and therefore a percentage of the contained Li in the feedto the Hydrometallurgical process is as α-spodumene.

TABLE 10. SQ-XRD Data of the two CL/PIR Residue Types 75/25 CL/PIR 50/50CL/PIR Chemical Residue Drum Residue Drum Composition 1-5, wt % 7-14, wt% H(AlSi₂)O₆ 60.6 67.3 Spodumene beta 12.0 9.4 SiO₂ 11.6 7.5 NaAlSi₃O₈3.6 3.8 CaSO_(4·)(H₂O) 2.7 4.4 KAlSi₃O₈ 1.6 3.6 LiAlSi₂O₆ 2,2 2.5Ca(SO₄)(H₂O)0.5 2.5 — αFeO·OH 1.9 — Fe₃O₄ — 1.6 CaSO_(4·)2H₂O 1.1 —gamma-Mn₃O₄ 0.3 — 100.1 100.1 Li Bearing Mineral Relative Distributionof Li, % Spodumene beta 94.9 92.7 LiAlSi₂O₆, 5.1 7.3

The Li units that are in the CL/PIR residues as β-spodumene were neveravailable to the process and as a result provide a false low Li recoveryvalue.

An adjusted Li recovery was calculated that did not consider the Liunits tied up as β-spodumene in the CL/PIR residue. The data for thiscalculation are summarized in Table 11. The total Li in all of the outprocess streams was about 63.2 kg. This included about 11.7 kg of Li inthe CL/PIR residue that was present as β-spodumene. The adjusted totalLi out value thus becomes about 51.6 kg. The total recoverable Li by theoverall process was about 46.9 kg. The adjusted total Li recovery isthen calculated to be about 95.8%.

TABLE 11 Adjusted Total Li Recovery Li Mass, g Total Li OUT based onAssays 60615 Total Li Recovered 46884 Total Li in CL/PIR Residue asβ-Spodumene 11655 Total Li OUT minus Li as β-Spodumene 48960 AdjustedTotal Li Recovery, % 95.8

A high grade lithium sulphate solution was thus produced. In accordancewith FIG. 1, this solution can be used, for example, as the lithiumsource in the production of a solution of high quality lithium hydroxideand/or high quality lithium carbonate. This high grade lithium sulphatesolution can also be used as a feed in the production of other highgrade lithium products.

EXAMPLE 2

Electrolysis: Conversion of Li₂SO₄ into LiOH.

The electrolysis was conducted using an electrolysis method in athree-compartment membrane electrolysis (ME) cell. The centralcompartment of the ME cell was separated from the cathodic compartmentby a cationic membrane and from the anodic compartment by an anionicmembrane. The cathodes comprised stainless steel (316) and the anodecomprised a Ti mixed metal oxide (MMO) layer. The basic schematic of theME cell is provided in FIG. 17. The central compartment of the cell wascharged with low concentration lithium sulphate solution. The cathodiccompartment was filled with lithium hydroxide solution. The anodiccompartment was charged with dilute sulphuric acid solution at about 30g/L acid.

Under the influence of an electric field, lithium ions from the centralcompartment were transported through the cationic membrane into thecathodic compartment. In parallel, the sulphate ions moved through theanionic membrane into the anodic compartment. Meanwhile, hydroxyl ionsare produced on the cathode and hence lithium hydroxide is formed in thecatholyte. The anodic reaction generated protons resulting in theproduction of sulphuric acid as the anolyte. As a result the lithiumconcentration increases in the catholyte and drops in the centralcompartment during membrane electrolysis. During operation the Li tenorin the central compartment was maintained by the controlled addition ofa concentrated lithium sulphate solution.

The cathodic and anodic compartments are fed with deionized water inorder to keep the lithium hydroxide and sulphuric acid concentrations atpredetermined levels.

The synthesis of lithium hydroxide was conducted using a stacked ME cellconsisting of two three-compartment cells. The main components of thecell were fabricated with high density polypropylene (HDP). The cathodescomprised 316 stainless steel and were about 100 cm×about 50 cm. Theanode was coated with titanium mixed metal oxide (MMO) and was about 100cm×about 50 cm. The anode was purchased from De Nora Tech (part number:DNT-DX-09-118 Electrowinning Anodes sheet, coating code DN-475E bothsides).

The stack design of the ME cell allowed for essentially two ME cellsthat operated in parallel. Further, the stacked configuration allowedfor the anode to be shared by the two cells. Each cell comprises acathodic compartment equipped with a cathode, a central compartment andan anodic compartment with the shared electrode. The central compartmentof the cell was separated from cathodic compartment by a cationicmembrane Lanxess Ionac™-MC-3470 and from the anodic compartment by ananionic membrane Lanxess Ionac™-MA-7500. Effective working area of eachmembrane was about 0.84 m². The void space within each compartment wasfilled with polypropylene mesh to aid in dispersing the solution flow.The process flow diagram of the ME circuit is provided in FIG. 18.

The electricity to the ME cell was supplied by a direct currentrectifier unit, type SR DDS-5C024-02 manufactured by Hanson. Therectifier had both an amp meter and a volt meter that were used formonitoring the voltage and current applied to the cell. The rectifierwas set on current control mode.

The lithium sulphate solution produced in the previous sections was usedas a lithium source for the ME pilot plant (electrolysis). Thecomposition of the feed solution is provided in Table 12.

TABLE 12 Composition of Feed Solution Tenor of solution components, mg/LSample ID Li Na K Ca Mg Fe Zn IX 15700 3980 107 3.8 0.2 <0.2 <0.7Product Ag Al As Ba Be Bi Cd Carboy 1 <0.5 <0.8 <3   0.03 <0.002 <1  <0.3 Co Cr Cu Mn Mo Ni P mg/L <0.3 <0.2 <0.1 <0.04 <0.6 <1   <5   Pb SbSe Sn Sr Ti Tl <2   <1   <3   <2 0.61 <0.1 <3   U V W Y SO4 Cl <1   <0.07 <2   <0.02 120000 5 

The ME cell was pre-filled prior to the start of the pilot plant. Thecentral compartment of the cell was charged with an aqueous compositioncomprising lithium sulphate Feed solution that had been diluted down toabout 2 g/L Li with RO water (thus about 15.8 g/L of Li₂SO₄). Thecathodic compartment was filled up with an aqueous compositioncomprising lithium hydroxide. About sixty litres of an aqueouscomposition comprising sulphuric acid (about 30 g/L) was prepared fromreagent acid and used to fill the anodic compartment. The composition ofthe starting material compositions were thus as follows (see Table 13).

TABLE 13 Compositions of Starting Material Compositions Tenor ofsolution components, mg/L Sample ID Li Na K Ca Mg Fe Zn Spent-Init 1300452 14 <0.9 <0.07 <0.2 <0.7 Ca-Init 3100 740 30 <0.9 <0.2 <0.07 <0.7An-Init 0.07 <2 <1 <0.9 <0.07 <0.2 <0.7 Ag Al As Ba Be Bi Cd Spent-Init<0.5 <0.8 <3 <0.007 <0.002 <1 <0.3 Ca-Init <0.5 <0.8 <3 <0.007 <0.002 <1<0.3 An-Init <0.5 <0.8 <3 <0.007 <0.002 <1 <0.3 Co Cr Cu Mn Mo Ni PSpent-Init <0.3 <0.2 <0.1 <0.04 <0.6 <1 <5 Ca-Init <0.3 <0.2 <0.1 <0.04<0.6 <1 <5 An-Init <0.3 <0.2 <0.1 <0.04 <0.6 <1 <5 Pb Sb Se Sn Sr Ti TlSpent-Init <2 <1 <3 <2 0.077 <0.02 <3 Ca-Init <2 <1 <3 <2 0.049 <0.02 <3An-Init <2 <1 <3 <2 <0.002 <0.02 <3 U V W Y SO4 Cl Spent-Init <1 <0.2 <2<0.02 13000 <1 Ca-Init <1 <0.2 <2 <0.02 An-Init <1 <0.2 <2 <0.02 24000<1

The central compartment of the cell was fed with the fresh aqueouscomposition comprising lithium sulphate (Feed). The feed flow rate wascontrolled to maintain about 2 g/L of Li in the central compartment(about 15.8 g/L of Li₂SO₄). The pH of the aqueous composition comprisinglithium sulphate in the central compartment was maintained at a value ofabout 10 to about 12.

The spent electrolyte from central compartment was bled to the spentbleed tank. The bleed was taken from recirculation tubing beforereaching the reservoir to ensure a low lithium tenor in the spentelectrolyte. The bleed flow rate was controlled to maintain a constantlevel in the reservoir tank. The anolyte had both a bleed flow from theanolyte reservoir and a dilution water flow to the reservoir. The bleedflow rate was controlled to maintain level in the anolyte reservoir byhaving the bleed tubing at a fixed level in the tank and ensuring thepump was set higher than the dilution water flow rate. The dilutionwater flow rate was controlled to maintain a concentration of about 30g/L concerning the aqueous composition comprising sulphuric acid (in theanodic cell (as monitored by free acid titrations)). The catholyte alsohad both a bleed flow and a dilution water flow to the reservoir. Thebleed flow rate for the catholyte was controlled to maintain level inthe reservoir. The bleed was taken from the recirculation tubing beforereaching the reservoir to ensure a high Li tenor and no contamination.Dilution water for the catholyte was added to maintain lithium tenor atabout 15 g/L (about 51.8 g/L in terms of LiOH) in the catholyte product(aqueous composition comprising LiOH). These flows are illustrated inFIG. 18.

Grab samples from the central compartment (the spent solution) weretaken every about 4 hours, profile samples were taken every about 6hours and composite samples were taken every about 12 hours of theanolyte and every about 24 hours for the spent and catholyte. Titrationsfor lithium hydroxide in the catholyte and free acid titrations for theanolyte were done once an hour.

The ME pilot plant ran in two 5 day sections: Week 1 and Week 2. Eachsection operated continuously for the five days. Hourly readings weretaken to monitor current, voltage, temperature, the flow rates, andproduct and feed weights. All of the readings were recorded in anOperation Log sheet. At start-up a current of about 400 A was applied tothe cell. The recirculation flow rate was set at about 3 L/min and thetemperature set points on the cooling water for the circulation tankswas set to about 40° C. During the operation of the pilot plant severalchanges were made to operating conditions in order to determine theeffect the changes would have on production. The first change involvedincreasing the amperage from about 400 A to about 440 A, to see if itwould be possible to increase the feed flow rate without decreasing theproduct Li tenor. Next the recirculation speed was increased from about3 to about 6 L/min, to see if this would improve the efficiency of thecell. Another test carried out was to operate on voltage control ratherthan amperage control, by trying to achieve and maintain about 10 toabout 12 V. Finally, the temperature set point on the cooling water forthe recirculation tanks was changed to about 50° C. and about 35° C.Membrane electrolysis operation conditions are summarized in Tables 14and 15.

TABLE 14 ME Pilot Plant Operation Conditions. Week One ElectrolysisCurrent Time Current time quantity Power Circ. Rate Temp. From To A h AhWh L/min ° C. Day 1 12-11 23:47 12-11 23:59 400 0.2 85 710 3 40 12-0510:43 12-05 23:59 400 13.3 5287 44837 3 40 12-06 0:00 12-06 6:00 400 6.02398 19040 3 40 Total 19.5 7770 64586 Day 2 12-06 6:01 12-06 14:28 4008.4 3373 31638 3 40 12-06 14:29 12-06 23:59 440 9.5 4164 43448 3 4012-07 0:00 12-07 5:59 440 6.0 2619 28855 3 40 Total 23.9 10156 103941Day 3 12-07 6:00 12-07 10:37 440 4.6 2026 24327 3 40 Run 440 A 20.1 880996629 12-07 11:40 12-07 23:59 400 12.3 4915 51481 3 40 12-08 0:00 12-085:59 400 6.0 2390 27229 3 40 Total 22.9 9332 103037 Day 4 12-08 6:0012-08 11:59 400 6.0 2392 31380 3 40 12-08 12:00 12-08 19:25 400 7.4 295927988 6 40 12-08 19:54 12-08 21:08 400 1.2 490 4274 6 40 12-08 21:1612-08 23:59 400 2.6 1029 9107 6 40 12-09 0:00 12-09 5:54 400 5.9 235721190 6 40 Total 23.1 9227 93939 Day 5 12-09 5:55 12-09 11:59 400 6.12423 22159 6 40 Run 6 L/min 23.2 9259 84717 12-09 12:00 12-09 15:29 4003.5 1394 17566 3 40 12-09 15:30 12-09 23:59 400 8.5 3385 37798 3 4012-10 0:00 12-10 5:00 400 5 1987 18703 3 40 Total 23.0 9190 96226 TotalWeek 1 113.0 45856 464366

TABLE 15 ME Pilot Plant Operation Conditions. Week Two ElectrolysisCurrent Time Current time quantity Power Circ. Rate Temp. From To A h AhWh L/min ° C. Day 6 12-11 23:47 12-12 0:00 400 0.2 85 710 3 40 12-120:00 12-12 5:54 400 5.9 2359 20381 3 40 Total 6.1 2444 21091 Day 7 12-125:55 12-12 11:58 400 6.0 2422 21166 3 40 12-12 11:58 12-12 23:59 42012.00 5029 49732 3 40 12-13 0:00 12-13 5:53 420 5.9 2468 26658 3 40Total 23.9 9920 97556 Day 8 12-13 5:54 12-13 17:55 420 12.0 5036 49160 340 12-13 17:56 12-13 23:59 420 6.05 2539 25817 3 40 12-14 0:00 12-145:53 420 5.9 2470 24367 3 40 Total 24.0 10044 99344 Day 9 12-14 5:5412-14 7:58 420 2.1 869 8335 3 40 12-14 8:37 12-14 18:00 420 9.4 393338591 3 40 12-14 18:01 12-14 23:59 420 6.0 2502 25998 3 40 12-15 0:0012-15 5:51 420 5.9 2456 24553 3 40 Total 23.3 9761 97477 Day 10 12-155:52 12-15 17:59 420 12.1 5078 42651 3 40-50 12-15 18:00 12-15 19:15 4201.3 529 4793 3 35 12-15 19:16 12-15 22:14 360-450 3.0 1273 12735 3 3512-15 22:15 12-15 23:59 420 1.7 733 6854 3 35 12-16 0:00 12-16 5:52 4205.9 2466 22448 3 35 Total 23.9 10079 89480 Day 11 12-16 5:53 12-16 21:00420 15.1 6337 61175 3 35 Test t = 35° C. 26.9 11338 108004 Total 15.16337 61175 Total Week 2 116.3 48585 466122

During the two 5-day pilot plants about 621 litres of the aqueouscomposition comprising lithium hydroxide and having a concentration ofabout 14.6 g/L of lithium (or about 49.9 g/L of lithium hydroxide) andabout 2239 litres of the aqueous composition comprising sulphuric acidat a concentration of about 20 to about 30 g/L were produced. A total ofabout 675.8 litres of the aqueous composition comprising lithiumsulphate was processed and about 425 litres of spent electrolytecontaining about 2 to about 3 g/L of lithium was produced. Masses,volumes and densities of products produced are provided in Tables 16 and17. The ME process was conducted for about 228 hours. During theoperation about 930.5 kWh of electrical energy was consumed for lithiumsulphate conversion to lithium hydroxide.

TABLE 16 ME Pilot Plant Products. Week One Anolyte Spent Catholyte FeedVol- Vol- Vol- Vol- Mass ume Mass ume Mass ume Mass ume Time kg L kg Lkg L kg L Initial 60 59.1 60.2 59.5 40 39.5 solution Day 1 235.8 231.770.8 69.6 6.6 6.3 87.3 78.9 Day 2 274.5 269.8 42.84 42.2 80.7 75.9 93.584.5 Day 3 270.5 266.0 40.61 40.1 83.0 78.6 88.7 80.2 Day 4 261.2 257.235.94 35.5 74.6 70.6 81.4 73.5 Day 5 225.8 222.1 35.10 34.6 65.2 61.674.1 66.9 Final 60 59.0 60.2 59.4 53.6 50.6 solution Total 1267.8 1246.7225.3 221.9 310.2 315.1 425.0 384.0 Week 1

TABLE 17 ME Pilot Plant Products. Week Two. Anolyte Spent Catholyte FeedVol- Vol- Vol- Vol- Mass ume Mass ume Mass ume Mass ume Time kg L kg Lkg L kg L Initial 60 59.0 60.2 59.4 53.5 50.5 solution Day 6 64.5 63.610.3 10.0 13.4 12.7 19.6 17.7 Day 7 238.5 234.6 42.50 41.9 74.9 70.876.4 69.1 Day 8 233.4 229.5 45.01 44.3 75.3 71.1 75.3 68.1 Day 9 206.8203.6 56.67 56.0 56.1 53.1 60.9 55.0 Day 10 165.2 162.7 53.2 52.5 46.243.7 54.1 48.9 Day 11 116.6 114.6 35.3 34.9 34.5 32.7 36.6 33.1 Final43.6 42.9 24.0 23.8 76.0 72.0 solution Total 1008.6 992.6 206.8 204.0322.9 305.6 268.9 291.9 Week 2

At the beginning, the starting material aqueous composition in thecathodic compartment contained only about 3.1 g/L Li (about 10.5 g/L ofLiOH). During electrolysis the lithium tenor in the catholyte increased.It took about 13 hours for the Li tenor to reach the level of about 15g/L (about 51.8 g/L of LiOH).

When the Li concentration in catholyte approached about 15 g/L (about51.8 g/L of LiOH), reverse osmosis water addition to the cathodiccompartment was started. The continuous mode of ME was then started. TheLi concentration in the catholyte was maintained by adjusting thedilution water flow to the catholyte reservoir. The Li concentration incatholyte grab samples was about 14 to about 18 g/L during the process(about 48.3 to about 62.1 g/L of LiOH). The Li tenor in the catholyte isplotted against electrolysis time during continuous electrolysis periodin first week of pilot plant operations in FIG. 19. During the secondweek of pilot plant operations the Li tenor was about 15 to about 16.3g/L (about 51.8 to about 56.2 g/L of LiOH) (FIG. 20). The Li assays forthe profile samples differ from Li tenor in grab samples. This happenedbecause the results were obtained by different methods. The Li tenors inthe grab samples were determined by titration with hydrochloric acid.The Li tenors in the profile samples were measured using atomicabsorption spectroscopy (AAS). The titration results indicate the totalhydroxide in solution, including hydroxides of Li, Na and K. The AASresults only report Li in solution.

Assay results of selected metals for the profile samples collected fromthe left and right line of the catholyte stream are listed in Table 18and Table 19. The catholytes of the left and right compartments wereclose in composition. The similarity of these values indicated thatelectrical current was distributed to both cathodes equally and bothcells were working with the same effectiveness.

TABLE 18 Assays for catholyte profile samples - Week One. Tenor, mg/LSampling Li Na K Ca Mg time Left Right Left Right Left Right Left RightLeft Right 05Dec 1800 8580 10900 2330 2770 82 101 1.6 1.9 <0.07 <0.0706Dec 0200 14100 14200 4090 4150 131 115 2.2 2.3 <0.07 <0.07 06Dec 100015000 14800 4070 4020 107 107 <0.9 2.1 <0.07 0.08 06Dec 1800 16100 161004450 4720 123 128 2.6 2.4 <0.07 <0.07 07Dec 0200 17200 17500 4050 4470119 119 2.7 2.7 <0.07 <0.07 07Dec 1000 17300 17700 3790 4130 139 137 2.92.9 <0.07 <0.07 07Dec 1800 15400 15900 3550 3470 114 123 2.6 2.5 <0.07<0.07 08Dec 0200 13900 13800 3220 3590 115 114 2.6 2.6 <0.07 <0.07 08Dec1000 13300 13700 3450 3680 111 115 2.9 3.2 <0.07 <0.07 08Dec 1800 1390014100 3540 3650 102 104 3.2 3.2 <0.07 <0.07 09Dec 0200 14900 15000 39404150 123 117 3.1 3.2 <0.07 <0.07 09Dec 1000 16100 15800 4380 4580 127118 3.8 3.5 <0.07 <0.07 09Dec 1800 15500 15600 3840 3660 103 101 3.6 3.4<0.07 <0.07 10Dec 0200 16500 13700 3920 3880 114 117 3.8 3.6 <0.07 <0.07

TABLE 19 Assays for Catholyte Profile Samples - Week Two Tenor, mg/LSampling Li Na K Ca Mg time Left Right Left Right Left Right Left RightLeft Right 12Dec 0200 15300 14900 3410 3360 115 124 3.3 3.7 <0.07 <0.0712Dec 1000 13900 14400 6110 3820 111 114 3.6 3.7 <0.07 <0.07 12Dec 180016100 16500 4240 3690 118 116 4 3.9 <0.07 <0.07 13Dec 0200 16200 164003480 3510 114 110 3.5 3.3 <0.07 <0.07 13Dec 1000 14500 14600 3430 3170118 109 4 3.6 <0.07 <0.07 13Dec 1800 14600 14400 4070 4020 119 157 4.23.9 <0.07 <0.07 14Dec 0200 16200 16600 3810 3700 126 129 3.8 3.7 <0.07<0.07 14Dec 1000 16000 15700 3770 3720 124 135 3.7 4.1 <0.07 <0.07 14Dec1800 15200 14800 3690 3870 133 134 3.9 3.9 <0.07 <0.07 15Dec 0200 1470014400 3560 3720 101 109 3.7 3.8 <0.07 <0.07 15 Dec 1000 14400 14300 38703980 125 128 3.7 3.8 <0.07 <0.07 15Dec 1800 14800 15300 4040 4240 138141 3.8 3.9 <0.07 <0.07 16Dec 0200 14700 14700 3870 3860 129 125 3.6 3.4<0.07 <0.07 16Dec 1000 13900 14000 3900 3880 124 126 3.9 3.8 <0.07 <0.0716Dec 1800 14000 15600 4120 4270 130 132 4 4 <0.07 <0.07

Lithium hydroxide solution was collected in batches over a 24 h period.The batches were switched out during the Day shift operation. A samplefrom each drum was taken as day composite sample. Assay results forcomposite samples are listed in Tables 20 and 21.

The LiOH concentration in product batches starting the second day ofpilot plant operation were about 47.3 to about 55.6 g/L (about 14 toabout 16 g/L of Li). The obtained aqueous composition also comprisedabout 3.3 to about 4.5 g/L of Na, about 0.11 to about 0.18 g/L of K andabout 2 to about 3.9 ppm Ca. Other impurities were present innon-significant amounts or were below the detection limit of theanalytical method.

TABLE 20 Assays for Catholyte Composite Samples: Week One SamplingTenor, mg/L time Li Na K Ca Mg Ba Sr Fe 11Dec-Init 14800 3630 108 3.5<0.07 0.06 0.56 0.5 12Dec 0600 14500 3260 117 3.9 0.55 0.058 0.63 0.713Dec 0600 14600 3640 117 3.7 <0.07 0.047 0.646 <0.2 14 Dec 0600 155003560 110 3.8 0.16 0.04 0.61 <0.2 15Dec 0600 14100 3570 129 3.9 <0.070.037 0.629 <0.2 16Dec 0600 13700 3640 124 4 <0.07 0.035 0.63 <0.2 16Dec2100 14200 3550 182 3.7 <0.07 0.02 0.6 <0.2 16Dec Final 16100 3390 1193.6 <0.07 0.03 0.59 0.2

TABLE 21 Assays for Catholyte Composite Samples: Week Two SamplingTenor, mg/L time Li Na K Ca Mg Ba Sr Fe 11Dec-Init 14800 3630 108 3.5<0.07 0.06 0.56 0.5 12Dec 0600 14500 3260 117 3.9 0.55 0.058 0.63 0.713Dec 0600 14600 3640 117 3.7 <0.07 0.047 0.646 <0.2 14 Dec 0600 155003560 110 3.8 0.16 0.04 0.61 <0.2 15Dec 0600 14100 3570 129 3.9 <0.070.037 0.629 <0.2 16Dec 0600 13700 3640 124 4 <0.07 0.035 0.63 <0.2 16Dec2100 14200 3550 182 3.7 <0.07 0.02 0.6 <0.2 16Dec Final 16100 3390 1193.6 <0.07 0.03 0.59 0.2

At the beginning of pilot plant operation the Li tenor in the spentelectrolyte fluctuated between about 1.5 and about 3.5 g/L. The Li tenorwas stabilized by adjusting of feed flow rate to the central compartmentof the cell. Spent electrolyte collected from the central compartment ofthe cell at steady state conditions contained about 2.1 to about 2.7 g/Lof Li, about 0.36 to about 0.49 g/L of Na and about 8 to about 14 mg/Lof K.

The sulphate tenors in anolyte profile samples are plotted in FIGS. 21and 22. The sulphate tenor in the anolyte solution fluctuated throughthe range of about 26 to about 39 g/L during the first week of pilotplant operation. The level of sulphuric acid during the second week,ranged from about 26 g/L to about 32 g/L.

Data obtained during pilot plant operation were used for calculations oflithium conversion rate, electrical current utilization efficiency,current quantity and power consumption for synthesis of lithiumhydroxide. Calculations have been done for each day and week of pilotplant operations as well as for each period of different operationconditions. Calculations were based on amounts of materials producedduring pilot plant campaign and based on concentrations changes insolutions floating in membrane electrolysis cell. Lithium hydroxidesynthesis conditions and calculated parameters are summarized in Tables22 and 23.

TABLE 22 Lithium Hydroxide and Sulphuric Acid Synthesis Parameters -Week One Electrolysis Current Circ. Li trans- Current Current timequantity Power Rate Temp. Compart- ferred effic. Formed LiOH/H₂SO₄ TestID A h A*h Wh L/min ° C. ment g % g g/h g/A*h g/kWh Day 1 400 19.5 777064586 3 40 Cathodic 734 36.5 2532 130 0.33 39.2 Central 1014 50.4 3497180 0.45 54.2 Anodic 51.7 7353 377 0.95 113.8 Day 2 400-440 23.9 10156103941 3 40 Cathodic 1241 47.2 4281 179 0.42 41.2 Central 1179 48.1 4068170 0.40 39.1 Anodic 48.3 8980 375 0.88 86.4 440 A 440 20.1 8809 96629 340 Cathodic 1006 44.1 3471 173 0.39 35.9 Central 1078 47.3 3720 185 0.4238.5 Anodic 45.1 7272 362 0.83 75.3 Day 3 400-440 22.9 9332 103037 3 40Cathodic 939 38.9 3241 141 0.35 31.5 Central 1167 48.3 4025 176 0.4339.1 Anodic 43.3 7390 322 0.79 71.7 Day 4 400 23.1 9227 93939 3-6 40Cathodic 1112 46.5 3836 166 0.42 40.8 Central 1165 41.3 3407 147 0.3736.3 Anodic 39.6 6681 289 0.72 71.1 6 L/min 400 23.2 9259 84717 6 40Cathodic 998 41.6 3443 148 0.37 40.6 Central 958 39.9 3305 142 0.36 39.0Anodic 37.8 6403 276 0.69 75.6 Day 5 400 23.0 9190 96226 6-3 40 Cathodic868 36.5 2996 130 0.33 31.1 Central 971 40.8 3351 145 0.36 34.8 Anodic39.1 6581 286 0.72 68.4 Total 400-440 113.0 45856 464366 3-6 40 Cathodic4894 41.2 16887 149 0.37 36.4 Week 1 Central 5445 45.9 18788 166 0.4140.5 Anodic 44.0 36893 327 0.80 79.4

The membrane electrolysis stack of two cells equipped with LanxessIonac™ membrane, with an effective working area of about 0.84 m²,provided the possibility to produce up to about 179 g of lithiumhydroxide per hour. The lithium conversion process performed with acurrent efficiency of about 43.5% during the first week and at about34.9% during the second week of pilot plant operation. The averageamount of lithium hydroxide produced by per about 1 kWh of electricalenergy was about 38.4 g and about 32.5 g for the first and the secondweek of pilot plant operation, respectively.

TABLE 23 Lithium Hydroxide and Sulphuric Acid Synthesis Parameters -Week Two Electrolysis Current Circ. Li trans- Current Current timequantity Power Rate Temp. Compart- ferred effic. Formed LiOH/H₂SO₄ TestID A h A*h Wh L/min ° C. ment g % g g/h g/A*h g/kWh Day 6 400 6.1 244421091 3 40 Cathodic 228 36.0 787 129 0.32 37.3 Central 293 46.3 1012 1660.41 48.0 Anodic 40.4 1569 257 0.64 74.4 Day 7 400-420 23.9 9920 97556 340 Cathodic 1077 41.9 3716 155 0.37 38.1 Central 1086 42.3 3749 157 0.3838.4 Anodic 39.6 7186 300 0.72 73.7 Day 8 420 24.0 10044 99344 3 40Cathodic 1140 43.8 3933 164 0.39 39.6 Central 940 36.1 3243 135 0.3232.6 Anodic 37.3 6850 286 0.68 69.0 Day 9 420 23.3 9761 97477 3 40Cathodic 659 26.1 2274 98 0.23 23.3 Central 765 30.3 2639 113 0.27 27.1Anodic 33.4 5964 256 0.61 61.2 Day 10 360-450 23.9 10079 89480 3 35-50Cathodic 592 22.7 2044 85 0.20 22.8 Central 598 22.9 2062 86 0.20 23.0Anodic 25.5 4703 197 0.47 52.6 t = 35° C. 420 26.9 11338 108004 3 35Cathodic 755 25.7 2605 97 0.23 24.1 Central 803 27.3 2769 103 0.24 25.6Anodic 34.0 7059 262 0.62 65.4 t = 50° C. 420 6.0 2525 20022 3 50Cathodic 231 35.4 798 133 0.32 39.8 Central 147 22.5 509 85 0.20 25.4Anodic 22.4 1035 173 0.41 51.7 Day 11 420 15.1 6337 61175 3 35 Cathodic856 52.1 2952 195 0.47 48.3 Central 548 33.4 1891 125 0.30 30.9 Anodic27.0 3134 207 0.49 51.2 Total 400-420 116.3 48585 466122 3 35-50Cathodic 4544 36.1 15678 135 0.32 33.6 Week 2 Central 4229 33.6 14593125 0.30 31.3 Anodic 37.0 32933 283 0.68 70.7

It can thus be seen that various parameters have been tested. The personskilled in the art can thus infer that such tests provide a factualbasis for making a sound prediction concerning various modificationsthat can be done to this process and obtaining the same utility. Whenselecting parameters concerning the temperature, the person skilled inthe art will understand that such values can be selected as a functionof the tolerance of the membranes and the materials of construction ofthe ME cell. Tables 24 and 25 provide mass balance for both weeks oftests.

TABLE 24 Mass Balance. Week One. Materials Vol Assays, mg/L IN L Li Na KCa Mg Catholyte Initial 39.5 3100 740 30 <0.9 <0.07 Anolyte Initial 59.10.07 <2 <1 <0.9 <0.07 Central Initial 59.5 1880 452 14 <0.9 <0.07 Feedto Central 384.0 15700 3980 107 3.8 0.2 Water to 228.3 0 0 0 0 0catholyte Water to anolyte 1314 0 0 0 0 0 OUT L Li Na K Ca Mg CatholyteFinal 53.6 15100 3900 116 3.7 <0.07 Anolyte Final 59.0 0 0 0 0 0 CentralFinal 59.4 3015 588 12.7 <0.9 <0.07 Product 293.0 14040 3792 124 2.68<0.07 Anolyte product 1247 0 0 0 0 0 Spent 222 2340 505.7 11.1 <0.9<0.07 Materials Mass Elemental Mass, g IN kg Li Na K Ca Mg CatholyteInitial 40.0 122 29.2 1.2 0 0 Anolyte Initial 60.0 0 0 0 0 0.0 CentralInitial 60.2 112 27 1 0 0 Feed to Central 425 6029 1528 41 1.5 0.08Water to 228 0 0 0 0 0 catholyte Water to anolyte 1314 0 0 0 0 0 OUT kgLi Na K Ca Mg Catholyte Final 53.6 809 209 6 0.2 0 Anolyte Final 60.0 00 0 0 0.0 Central Final 60.2 179 35 1 0 0 Product 310 4208 1144 37 10.00 Anolyte product 1268 0 0 0 0 0 Spent 225 515 112 2 0 0 Sum IN 21286263 1584 43 2 0 Sum OUT 1977 5712 1500 47 1 0 Accountability % 92.991.2 94.7 107.9 67.3 n/a Distribution (Calculated Head), % Li Na K Ca MgCatholyte 87.8 90.2 93.1 100 n/a Spent 12.2 9.8 6.9 0 n/a Sumcheck 100100 100 100 n/a

TABLE 25 Mass Balance. Week Two. Materials Vol Assays, mg/L IN L Li Na KCa Mg Catholyte Initial 50.5 14800 3630 108 3.5 <0.07 Anolyte Initial59.0 446 199 10 <0.9 <0.07 Central Initial 59.4 5180 1500 55 <0.9 <0.07Feed to Central 291.9 15700 3980 107 3.8 0.2 Water to 284.6 0 0 0 0 0catholyte Water to anolyte 986 0 0 0 0 0 OUT L Li Na K Ca Mg CatholyteFinal 72.0 16100 3390 119 3.6 <0.07 Anolyte Final 42.9 0 2 0 0 0 CentralFinal 23.8 2300 356 8 <0.9 <0.07 Product 284 14433 3537 130 3.8 0.4Anolyte product 993 0 0 0 0 0 Spent 239.6 2783 517 13 <0.9 <0.07Materials Mass Elemental Mass, g IN kg Li Na K Ca Mg Catholyte Initial53.5 747 183.3 5.5 0.2 0 Anolyte Initial 60.0 26 12 1 0 0 CentralInitial 60.2 308 89 3 0 0 Feed to Central 269 4583 1162 31 1.1 0.06Water to 285 0 0 0 0 0 catholyte Water to anolyte 986 0 0 0 0 0 OUT kgLi Na K Ca Mg Catholyte Final 76 1159 244 9 0.3 0 Anolyte Final 43.6 0 00 0 0 Central Final 24 55 8 0 0 0 Product 300 4132 1017 36 1.1 0.02Anolyte product 1009 0 0 0 0 0 Spent 243 606 109 2.6 0 0 Sum IN 17135664 1446 40.5 1.3 0.06 Sum OUT 1696 5952 1378 47.2 1.4 0.02Accountability % 99.0 105.1 95.3 116.3 105.3 31.5 Distribution(Calculated Head), % Li Na K Ca Mg Catholyte 88.9 91.5 94.1 99.2 100Spent 11.1 8.5 5.9 0.8 0.0 Sumcheck 100 100 100 100 100

In view of the above examples, it can be the that the contained lithiumsulphate in the AR β-spodumene was leached with an efficiency of about100%. It was observed that a retention time in the range of about 30 toabout 45 minutes was sufficient for the CL. It was demonstrated that theCL and PIR circuits can operate without necessarily having aliquid-solid separation step between the two circuits. The limeconsumption was about 350 kg dry equivalent mass of lime per about 1000kg of lithium carbonate equivalent (LCE).

It was also demonstrated that the SIR circuit can be operated in acontinuous manner. Impurities such as calcium and magnesium were reducedto levels that can efficiently be processed through ion exchangecolumns. The consumption of NaOH was about 10 kg per about 1000 kg LCE.It was determined that calcium continued to precipitate from solutionafter this solution had left the SIR circuit. In one such example thecalcium tenor in the SIR 4 reactor was about 286 mg/L. The filtrate ofthis solution on sitting for several hours had a calcium tenor of about140 mg/L. The SIR product slurry was approximately about 0.4% solids byweight. These solids had a Li content of about 4.4% and accounted forabout 0.5% of the total Li processed.

The processes were effective for reducing the calcium and magnesiumtenors in the lithium sulphate solution to below about 10 mg/L.

The processes were effective for removing about 97.6% of the containedcalcium and about 99.0% of the contained magnesium from the lithiumsulphate solution. Therefore, a high purity and high quality lithiumsulphate was produced. Only about 2.7% of the lithium was removed by theprocesses.

The process involving the electrolysis carried out by membraneelectrolysis in the three-compartment cell was effective for convertinglithium sulphate to lithium hydroxide. It was demonstrated that thelithium hydroxide production from lithium sulphate could operate in acontinuous manner using a three-compartment membrane electrolysis cell.The aqueous composition comprising lithium hydroxide was produced in thecathodic compartment, sulphuric acid was formed in the anodiccompartment and a composition having a low tenor in lithium sulphateoverflowed from the central compartment. The pilot plant produced about621 litres of an aqueous composition comprising lithium hydroxide havinga concentration of about 14.6 g/L of lithium (about 50.4 g/L of lithiumhydroxide) and about 2239 litres of sulphuric acid having aconcentration of about 20 to about 30 g/L. The lithium hydroxide thatwas produced was of a good quality. The aqueous composition comprisinglithium hydroxide solution contained about 3.7 g/L of sodium and about121 mg/L of potassium. The trace impurities present at levels of lessthan about 10 mg/L in the lithium hydroxide were Ba, Ca, Cr, Cu, Fe, Mg,Mn and Sr.

It was found that such a conversion of Li₂SO₄ into LiOH can beefficiently carried out in even in the presence of up to about 20 orabout 25% by weight of sodium based on the total weight of sodium andlithium. Such processes of the disclosure for converting Li₂SO₄ intoLiOH are thus effective for carrying out such a chemical reaction evenif the feed is not of high purity. That allows for saving costs sincecertain purification steps, prior to electrolysis or electrodialysis canbe avoided.

EXAMPLE 3

Conversion of LiOH into Li₂CO₃

The lithium carbonate production mini-pilot plant comprised twocircuits—the Lithium Hydroxide Carbonization Circuit (LC) and theLithium Bicarbonate Decomposition Circuit (DC). All equipment that camein contact with the process solutions was made of either glass, plasticor Teflon®. Due to the highly corrosive and quality sensitive nature ofthe fluids, no metal was introduced to the process.

Lithium hydroxide solution produced from Example 2 was used as a feedfor the lithium carbonate production. Tenors of select metals in thefeed are listed in Table 25. The tenor in Li thus ranged from about 14g/L to about 15.5 g/L (or the tenor of LiOH ranged from about 48.3 g/Lto about 53.5 g/L).

TABLE 25 Select Assay Data of the Lithium Hydroxide Solution Elementtenor, mg/L Sampling Li Na K Ca Mg Ba Sr Fe Feed Start 15100 3830 1103.2 <0.07 0.061 0.589 <0.2 28MAR 0600 15300 3780 123 3.8 <0.07 0.0640.602 <0.2 29 Mar 0600 14000 3640 112 3.2 <0.07 0.057 0.562 <0.2 30MAR0600 14300 3630 120 3.7 <0.07 0.065 0.637 <0.2 Average 14675 3720 1163.5 <0.07 0.062 0.598 <0.2

The LC circuit scheme is provided in FIG. 23. The lithium hydroxidecarbonization (LC) process was conducted in an enclosed 4 L Pyrex®reactor. The reactor was equipped with an overhead impeller, sparger,level controller, pH probe and thermocouple. For example, a burp-typesparger can be used for CO₂ addition. The sparger was located below theimpeller. For example, the below disposed sparger can ensure fulldispersion of the gas. The CO₂ flow was controlled by pH of reactionslurry using a solenoid valve.

Peristaltic pumps were used for transferring solutions and slurries. Theprocess slurry from LC was continuously pumped to the LC clarifier,where the solids were permitted to settle and the solution phase couldcontinuously overflow back into the LC reactor. The clarifier solidswere harvested from the clarifier underflow on a per shift basis andfiltered through Whatman® #3 filter paper. The filter cakes wereflood-washed in triplicate with hot reverse osmosis water and then driedon Pyrex® trays in an oven set to about 105 to about 110° C. Therecovered filtrate was returned back to the LC circuit.

The LC reactor level was maintained at a constant volume of about 3 L bythe level sensor controlling the bleed pump to the DC circuit. The LCcircuit bleed line advanced LC clarifier overflow to the DC reactor. TheDC circuit scheme is provided in FIG. 24. The DC process was conductedin an enclosed 4 L Pyrex® reactor. The reactor was placed in an electricheating mantle and equipped with an overhead impeller, pH probe andthermocouple. The solution in the DC Reactor was heated to about 95° C.in order to decompose lithium bicarbonate and drive the remaininglithium carbonate from solution. The resulting slurry was pumped to aheated clarifier. A bleed was taken from the top of the clarifier andcollected in a DC Filtrate drum. The slurry level in the DC reactor wasmaintained by positioning the DC bleed tubing inlet in the clarifier ata fixed level and setting the bleed pump to a greater flow rate thanthat of the feed to the DC reactor. The thickened pulp was harvested ona per shift basis. The filtered cake was treated in the same manner asthe LC reactor solids. The resulting solids represented a secondarylithium carbonate product. This DC solid stream was kept separate fromthe primary carbonate stream and was independently characterized.

Pilot Plant Operation

The Lithium Carbonate Production pilot plant ran continuously for 3days, 24 hours per day, with three shifts of 8 hours each. Hourlyreadings were taken to monitor temperature and pH in LC and DC reactorsas well as input and discharge rates of feed, CO₂ and spent solution.Grab samples from the LC circuit bleed and DC circuit bleed werecollected every 4 hours and submitted for Atomic Absorption Spectroscopyfor lithium analysis (referred to as Li-AAS). These assays provided aquick feedback on the performance of the process. Composite samples werecollected from the LC and DC bleed streams every 4 hours and combinedinto 12-hour composite samples. The composite samples were analysed forLi-AAS and a spectrum of other elements using Inductively-Coupled Plasma(ICP scan). Feed grab samples were taken daily and submitted for Li-AASand ICP scan assays.

During the operation of the pilot plant, the feed flow to the LC reactorwas increased from about 30 to about 60 mL/min to observe the effect ofretention time on LiOH carbonization efficiency. The operationconditions of the pilot plant are listed in Table 26.

TABLE 26 Conditions of Pilot Plant Operation LC circuit DC circuit CO₂Clari- Feed flow Reactor fier Temp Mixing flow actuated temp temp.Mixing Period ° C. RPM mL/min L/min ° C. ° C. RPM Start-up 15-32 600 00.5-1  Day 1 29-34 600 38-41 1-2 90-97 91-95 400 Cont. Night 1 34-37 60039-40 1.4-2.2 92-95 92-93 400 Day 2 34-36 600 39-45  1-2.2 91-97 92-94400 Night 2 31-36 600 44-45 1.4 91-96 92-93 400 Cont. Night 2 36 600 01.4-1.6 92-95 92-93 400 Batch Day 3 31-35 600 44-64 1.2-2.4 84-96 92-93400 Night 3 32-35 600 58-61 1.2-2.5 82-99 92-93 400

During the 3-day pilot plant campaign, about 12.5 kg of lithiumcarbonate was produced; about 9.9 kg of product was harvested from theLC reactor and about 2.6 kg from the DC reactor. The masses of Li₂CO₃solids produced during the pilot plant run are summarized in Tables 27and 28.

TABLE 27 Lithium Carbonate Solids Harvested from LC Circuit Dry WetProduct Batch Sample Cake Moisture weight # Date Time Identifier g % g 127-Mar 12:00 LC-Solids 24-Jun 38.3 334 2 27-Mar 20:17 LC-Solids 11-Dec36.7 681.3 3 28-Mar  1:30 LC-Solids 25-Jan 52.6 704.2 4 28-Mar 10:15 LCsolids 18-Jan 45.1 812.2 5 28-Mar 17:28 LC solids 13-Sep 38.2 610.2 628-Mar 22:00 LC solids 4-Apr 51.0 762.3 7 29-Mar  3:00 LC solids 31-Mar51.4 399.2 8 29-Mar 10:30 LC solids 29-Nov 45.5 778.6 9 29-Mar 19:36 LCsolids 22-Dec 35.7 933 10 29-Mar 10:30 LC solids 22-Mar 45.0 848.2 1130-Mar  3:45 LC solids 21-Jul 46.6 694 12 30-Mar  8:30 LC solids 14-Oct58.4 423.4 13 30-Mar 10:17 LC solids R 7-Apr 11.8 86.6 14 30-Mar 10:30LC solids R 4-Aug 39.7 351.7 15 2-Apr  8:52 LC SolidsPost 27-Sep 12.0881.6 2-Apr Reactor Scale 520 5-Apr Clarifier Scale 76.5 Total Solids16373 9897

TABLE 28 Lithium Carbonate Solids Harvested from DC Circuit Dry WetProduct Batch Sample Cake Moisture Weight # Date Time Identifier g % g 128-Mar 7:00 DC solids 28-May 27.1 374.7 2 29-Mar 6:00 DC solids 8-Mar17.9 355.8 3 30-Mar 0:30 DC solids 16-Aug 29.5 419.7 4 30-Mar 4:40 DCSolids 10-Jun 55.8 233.5 5 30-Mar 11:16  DC Solids 10-Sep 37.6 158.6 630-Mar 12:00  DC Solids R 5-Jan 15.5 930.8 8-Apr Reactor scale 140.011-Apr Clarifier scale 6.3 Total Solids 3426 2619

About 184 liters of lithium hydroxide solution containing about 14.7 g/Lof lithium was processed (or about 50.8 g/L of lithium hydroxide) andabout 161 litres of spent Li₂CO₃ solution containing about 1.39 g/Llithium were produced (or about 7.39 g/L of lithium carbonate). Massesand volumes of materials used daily are summarized in Table 29.

TABLE 29 Materials Used for Pilot Plant Operations Feed DC Filtrate CO₂Weight Volume Weight Volume Weight Volume Period kg L kg L kg L Initial3.17 3.0 Day 1 26.2 24.7 14.1 13.9 1.45 736 Night 1 29.0 27.4 26.4 26.11.4 701 Day 2 31.7 30.0 28.5 28.2 1.6 810 Night 2 27.7 26.2 22.78 22.51.38 702 Day 3 36.0 34.1 30.4 30.0 1.8 910 Night 3 44.3 41.9 41.2 40.72.2 1096 Total 194.9 184.4 163.4 161.4 9.7 4954

Results and Discussion

At the start of the test, the LC reactor was charged with lithiumhydroxide solution and agitated. The carbon dioxide flow was initiatedand within one and a half hours the pH of the reaction slurry waslowered from about 12.6 to the set point of about pH 11.0.

When the target pH was approached the continuous mode of the pilot plantoperation started. Addition of fresh lithium hydroxide solution to theLC reactor was started and the pH of the reaction slurry was maintainedat a value of about pH 11.0 by controlled addition of CO₂(g).

After about 2.5 hours of operation the overflow from the LC clarifierstarted and a bleed from the LC circuit was advanced to the DC reactor.It was expected that bleed solution from the LC reactor would containabout 3.5 to about 4 g/L Li as lithium carbonate. The Li tenor in LCcircuit overflow fluctuated around 4 g/L and the tenor values areplotted against elapsed time in FIG. 25.

Analytical data of the composite solutions from the LC circuit formetals with concentrations exceeding the analytical detection limits aresummarized in Table 30. A comparison of the LC bleed tenors to that ofthe LC feed solution (Table 25) indicated that Na and K tenors are onlyminimally affected by the LC process.

TABLE 30 Tenors of Selected Metals in Composite Samples from LC CircuitBleed Tenor mg/L Sample ID Li Na K Ca Mg Ba Sr 27Mar 1800 4150 3780 1062.3 0.07 <0.007 0.188 28Mar 0600 3940 3700 105 2.2 <0.07 <0.007 0.16428Mar 1800 4618 3380 99 1.7 <0.07 <0.007 0.162 29Mar 0600 4030 3600 1051.9 <0.07 0.009 0.148 29Mar 1800 4315 3640 106 2.3 <0.07 0.02 0.19730Mar 0600 4510 3710 110 2.4 <0.07 <0.007 0.175

The lithium tenor in the DC bleed was about 1240 to about 1490 mg/Lduring the pilot plant. A considerable depletion of Li tenor in lithiumcarbonate solution was observed in the DC process (compared with about2800 to about 4760 mg/L of Li in the LC bleed). Assay results forselected metals in the bleed from the DC circuit are summarized in Table31. Similar to the LC process, a minimal change in Na and K tenorsacross the DC process was observed (compared to the LC bleed and the DCbleed in Table 30 and Table 31).

TABLE 31 Tenors of Selected Metals in Composite Samples of Bleed from DCCircuit Tenor mg/L Sample ID Li Na K Ca Mg Ba Sr 28Mar 0600 1450 3850115 1.1 <0.07 <0.007 0.075 28Mar 1800 1449 3380 108 1.4 <0.07 <0.0070.081 29 Mar 0600 1230 3590 107 2 <0.07 0.021 0.068 29Mar 1800 1406 3610102 1.2 <0.07 0.011 0.079 30Mar 0600 1310 3530 103 2 0.1 <0.007 0.074Bleed Drum 1390 4010 103 1.4 <0.07 <0.007 0.08

The lithium tenor in the bleed from DC circuit is plotted againstoperation time in FIG. 26.

Table 32 summarizes the data on the LiOH feed solution and carbondioxide gas usage for each 12-hour period of pilot plant operation. Alsoincluded in Table 32 are the data on materials used for the periods ofbatch or continuous modes and for test with increased feed flow rate.Carbon dioxide was utilized with an efficiency of about 90.2% for theoverall pilot plant. Increasing the feed flow rate to the LC reactorfrom about 30 to about 60 mL/min had little impact on the CO₂utilization efficiency.

TABLE 32 Data on Carbon Dioxide Utilization Feed Li CO2 Li Con- Utiliza-Used tenor verted Needed Used tion Test ID L g/L g kg kg % Start-up 3.015.1 45.4 0.14 0.1 119.8 Day 1 Cont 21.7 15.1 328.3 1.04 1.3 78.5 Day 1total 24.7 15.1 373.7 1.18 1.4 81.9 Night 1 27.4 15.1 413.6 1.31 1.495.3 Day 2 30.0 15.3 459.5 1.46 1.6 91.6 Night 2 Cont1 18.8 15.3 287.70.91 1.0 95.5 Night 2 Batch 2.94 15.3 45.0 0.14 0.2 78.0 Night 2 26.215.3 401.5 1.27 1.4 92.2 Day 3 60 mL/min 19.1 14 267.0 0.85 1.0 82.2 Day3 total 34.1 14 477.1 1.51 1.8 84.6 Night 3 41.9 14.3 598.8 1.90 2.1588.2 Overall PP 184.4 2769.5 8.78 9.7 90.2

The assay data of the lithium carbonate solids produced during pilotplant are summarized in Tables 33 and 34.

Lithium carbonate samples from all batches, except “LC solids batch 13R”(Table 33), met the required specifications for lithium carbonate ofabout 99.9% purity. The Li₂CO₃ solids from batches “LC solids batch 12”and “LC solids batch 13R” were re-pulped and rewashed in an attempt toreduce the Na and K content of the solids. Dried products were submittedfor assay. The re-pulped lithium carbonate contained significantly loweramounts of Na and K. It follows from the washing test that Na and K, canbe removed from lithium carbonate solids by additional washing.

TABLE 33 Assay Results for Li₂CO₃ Solids Harvested from LC CircuitElements, % Sample ID Na K Ca Mg LC Solids Batch 1 0.007 <0.002 0.0025<0.00007 LC Solids Batch 2 0.009 <0.002 0.0028 <0.00007 LC Solids Batch3 0.014 <0.002 0.0023 <0.00007 LC Solids Batch 4 0.007 <0.002 0.0026<0.00007 LC Solids Batch 5 0.006 <0.002 0.0025 <0.00007 LC Solids Batch6 0.004 <0.002 0.0027 <0.00007 LC Solids Batch 7 0.004 <0.002 0.0028<0.00007 LC Solids Batch 8 0.013 <0.002 0.0021 <0.00007 LC Solids Batch9 0.011 <0.002 0.0026 <0.00007 LC Solids Batch 10 0.010 <0.002 0.0025<0.00007 LC Solids Batch 11 0.012 <0.002 0.0028 <0.00007 LC Solids Batch12 0.032 0.002 0.0027 <0.00007 Repulped Batch 12 0.007 <0.002 0.0026<0.00007 LC Solids Batch 13 R 0.042 0.003 0.0055 <0.00007 Repulped Batch13 R 0.024 <0.002 0.0052 <0.00007 LC Solids Batch 14R 0.009 <0.0020.0028 <0.00007 Post LC Prod 0.011 <0.002 0.0042 <0.00007

TABLE 34 Assay Results for Li₂CO₃ Solids Harvested from DC CircuitElements, % Sample ID Na K Ca Mg DC Solids Batch 1 <0.002 <0.002 0.003<0.00007 DC Solids Batch 2 <0.002 <0.002 0.0019 <0.00007 DC Solids Batch3 <0.002 <0.002 0.0019 <0.00007 DC Solids Batch 4 <0.002 <0.002 0.0014<0.00007 DC Solids Batch 5 <0.002 <0.002 0.0019 <0.00007 DC Solids Batch6 R 0.009 <0.002 0.0083 <0.00007

TABLE 35 Assay data for combined Li₂CO₃ products LC Prod LC Prod DC ProdDC Prod LC Post Analyte Spec Low Na High Na Low Ca High Ca Solids Na<400 ppm 60 100 <20 70 100 Sulphur (S) <200 ppm <100 <100 <100 <100 <100Chlorides (Cl) <100 ppm 19 14 22 21 22 Ca <100 ppm 28 28 18 64 49 Mg<100 ppm <0.7 <0.7 <0.7 <0.7 <0.7 K <50 ppm <20 <20 <20 <20 <20 B <10ppm <4 <4 <4 <4 <4 Fe <5 ppm <2 <2 <2 <2 <2 Cr <5 ppm <1 <1 <1 <1 <1 Ni<5 ppm <1 <1 <1 <1 <1 Cu <5 ppm <1 <1 <1 <1 <1 Pb <5 ppm <0.2 0.4 <0.2<0.2 <0.2 Al <5 ppm <4 <4 <4 <4 <4 Zn <5 ppm <1 1 <1 <1 <1 Mn <5 ppm<0.4 <0.4 <0.4 <0.4 <0.4 Li₂CO₃ Grade, % >99.5% 99.9893 99.9858 99.99499.9845 99.9829 LOD @ 110° C., % 0.35 0.42 0.32 0.29 0.33 LOI @ 500° C.,% 0.58 0.47 <0.1 <0.1 0.5 Note: Li₂CO₃ grade determined by difference

Moreover, the DC circuit product has a finer particle size than thesolids from the LC circuit:about 80% of particles in the DC product areunder about 57 μm compared to about 80% being under about 104 μm in theLC product.

A mass balance of the overall pilot plant is summarized in Table 36. Itis evident from the data provided in the table that about 88% of thelithium was converted to the lithium carbonate solids. Sodium andpotassium does not precipitate with lithium carbonate.

TABLE 36 Mass Balance Summary: Vol Wt Assays mg/L, g/t, % Materials L gLi Na K Ca IN Feed Day 1 39.0 15100 3830 110 3.2 Feed Day 2 58.0 153003780 123 3.8 Feed Day 3 65.8 14000 3640 112 3.2 Feed Day 4 21.6 143003630 120 3.7 CO₂ 4954 0 0.00 0.00 0.00 OUT DC Bleed 161.5 1390 4010 1031.4 DC filtrate 2.6 1680 4320 129 1.3 LC filtrate 0.4 3060 3680 109 1.7Post LC filtrate 2.1 1300 3860 119 <0.9 Wash 46.1 1850 851 25 1 Post LCwash 1.0 1890 851 25 1 LC Prod Low Na 4023 17.9 0.01 <0.002 28 LC ProdHigh Na 4310 18.3 0.01 <0.002 28 DC Prod Low Ca 1168 18.8 <0.002 <0.00218 DC Prod High Ca 1306 19.2 0.01 <0.002 64 LC Post Solids 881.6 17.90.01 <0.002 49 Scale solids 829.4 19.2 0.01 <0.002 64 Wt Weights, gMaterials kg Li Na K Ca IN Feed Day 1 41.2 588.5 149.3 4.3 0.1 Feed Day2 61.3 887.1 219.2 7.1 0.2 Feed Day 3 69.6 921.8 239.7 7.4 0.2 Feed Day4 22.8 308.4 78.3 2.6 0.1 CO2 9.7 0 0 0 0 Sum IN 205 2706 686 21.4 0.64OUT DC Bleed 163.5 224.5 647.6 16.6 0.2 DC filtrate 2.6 4.31 11.1 0.330.003 LC filtrate 0.4 1.1 1.3 0.04 0.001 Post LC filtrate 2.2 2.8 8.30.3 0 Wash 46.6 85.4 39.3 1.2 0.05 Post LC wash 1.0 1.9 0.9 0.0 0.001 LCProd Low Na 4.0 720 0.2 0 0.1 LC Prod High Na 4.3 789 0.4 0 0.1 DC ProdLow Ca 1.2 220 0 0 0.02 DC Prod High Ca 1.3 251 0.1 0 0.1 LC Post Solids0.9 158 0.1 0 0.04 Scale solids 0.8 159 0.1 0 0.1 Sum OUT 170 2616 70918.4 0.7 IN − OUT 35.1 89.9 −22.9 3.0 −0.1 Accountability % 82.9 96.7103.3 86.1 111.9 Distribution % Calculated Head Solids 87.8 0.1 0.0 61.0Spent 8.9 94.2 93.7 32.3 Wash 3.3 5.7 6.3 6.6 Sumcheck 100 100 100 100

It was thus demonstrated that sparging a lithium hydroxide solution withcarbon dioxide gas is an effective method for conversion of lithiumhydroxide to high-purity and high quality lithium carbonate. In fact,the average carbon dioxide utilization efficiency of the process wasabout 90%. It was also demonstrated that lithium carbonate productionfrom lithium hydroxide could operate in a continuous manner. A lithiumcarbonate production process comprising: i) lithium hydroxidecarbonization and ii) lithium bicarbonate decomposition andprecipitation, was shown to be efficient. Both (i) and (ii) produced ahigh grade lithium carbonate product. The pilot plant produced about12.5 kg of lithium carbonate solids having a Li₂CO₃ grade of >99.9%. Theachieved Li conversion from LiOH to Li₂CO₃ was about 88%. Sodium andpotassium did not co-precipitate with the Li₂CO₃.

EXAMPLE 4 Alternate Process Using Ammonia to Neutralize Acid

Applicant has previously shown in U.S. 61/788,292 (hereby incorporatedby reference in its entirety) that lithium hydroxide can be successfullyrecovered at high efficiencies from a lithium sulfate process stream attemperatures of about 40° C. or about 60° C., using electrolysis with aNafion 324 cation exchange membrane and either an Asahi AAV or aFumatech FAB anion exchange membrane. In both cases, sulfuric acid wasproduced as a coproduct. An alternate process where ammonium sulfate isproduced instead of sulfuric acid may be useful and the presentdisclosure details work demonstrating its feasibility. Tests wereperformed using a similar electrolysis cell as in U.S. 61/788,292,except that the highly resistive proton-blocking Fumatech™ FAB membranewas replaced with a Neosepta™ AHA membrane. The AHA membrane is an anionmembrane manufactured by Astom™ (Japan) with a higher temperaturestability (about 80° C.) that have good electrical resistance forsulfate transport.

Current efficiency for hydroxide production (about 80% at about 3 M)matched the highest obtained in the previous studies when the feed waskept at an about neutral pH. Salt production at very high efficiency wasinitially possible. However, as the batch proceeded the hydroxideinefficiency (about 20%) caused an increase in the feed pH and thehydroxide in the feed competed with sulfate transport across the AHAmembrane.

Based on the testing performed in the present studies, a continuousprocess using Nafion 324 and AHA membranes at about 60° C. would beexpected to have the following characteristics, and is compared withresults for the known Sulfuric Acid Process in Table 37 below.

TABLE 37 Comparison of Sulfuric Acid and Ammonium Sulfate ProcessesSulfuric Ammonium Acid Sulfate Process Process Recommended Process BatchContinuous Membranes N324/FAB N324/AHA Sulfuric Acid/Ammonium Sulfate  0.75M     3M Lithium Hydroxide 3-3.2M 3-3.2M Average Current Density100 mA/cm² 150 mA/cm² Current Efficiency for Hydroxide 75% 80% CellVoltage in Custom Cell 6 V 4.6 V Water Transport: Feed to Base 8 molwater 8 mol water per mol cation per mol cation Water Transport: Feed toAcid <1 mol water 12 mol water per mol cation per mol cation

Previous studies (U.S. 61/788,292) have shown that lithium hydroxide canbe successfully recovered at high efficiencies from a lithium sulfateprocess stream at temperatures of about 40° C. or about 60° C., usingelectrolysis with a Nafion 324 cation exchange membrane and either anAsahi AAV or a Fumatech FAB anion exchange membrane. In both cases,sulfuric acid was produced as a coproduct. The production of sulfuricacid can limit, for example the choice of anion membrane in the system,the acid concentration which can be achieved and the temperature ofoperation.

Certain anion exchange membranes such as a proton-blocking membranewhich has a high resistance especially for sulfate transport such as theFumatech FAB membrane or a similar membrane, may, for example limit thecurrent density achieved in a process for preparing lithium hydroxide.However, these membranes can be limited to a temperature of about 60° C.

Highly concentrated ammonium sulfate (>about 2 M) can be produced in asimilar electrolysis cell, and due, for example to the bufferingcapacity of bisulfate and the ability to dissolve ammonia in solution,it is possible to make the anolyte solution non-acidic as shown in FIG.27. In this way, proton-blocking anion exchange membranes, for examplemay not be required and alternative membranes, for example a NeoseptaAHA membrane which is capable of running at a temperature of about 80°C. and that should have lower resistance can be used.

Such a process may, for example remove the higher resistance FABmembrane possibly allowing operation at either higher current density(thereby reducing membrane area), lower voltage (thereby reducing powerconsumption) or a combination of the two. It may also, for example,generate an alternate commercial material. Ammonium sulfate can be soldas an ingredient for fertilizer and should have a higher value than thesulfuric acid. It is also, for example expected to remove more waterduring the electrolysis from the feed thereby allowing more efficientoperation over a wider range of feed conversion. It may also, forexample, allow operation of the process at a higher temperaturerequiring less cooling of solutions. Solutions and membranes are alsoless resistive at these higher temperatures decreasing powerconsumption.

The tests performed on this system, where the anion membrane used in theprevious process (Fumatech FAB) is replaced by a Neosepata AHA (AstomCorp.) membrane and ammonia is used to control the pH of the “acid”compartment of the cell are summarized below.

The experiments were carried out in an Electrocell MP cell similarlyequipped to that used in the previous studies (U.S. 61/788,292) butwherein the anion membrane was replaced with a Neosepta AHA (AstomCorp.) membrane.

The various electrolyte circuits were similar to those used in theprevious studies (U.S. 61/788,292), except that pH control was added tothe anolyte (acid/salt) circuit. The pH controller actuated a solenoidvalve which allowed addition of ammonia gas directly to the anolytereservoir. Care was taken to not allow the anolyte pH to increase aboveabout 5 as the DSA-O₂ coating can be removed at high pH. In addition tothose analyses previously performed, ammonium ion was analyzed by cationion chromatography. All other aspects of the experimental setup were thesame as described previously.

During the course of the present studies, experiments of varyingduration were performed. These experiments evaluated the effect oftemperature, current density, feed conversion, acid/salt concentration,base concentration and pH control strategy on current efficiencies,voltage and water transport. Concentration ranges and currentefficiencies are summarized in Table 38. In the first two experiments,the concentration of base and acid/salt were allowed to increase fromtheir starting values. The second experiment ran over two days toprovide a greater amount of sulfate removal. In this case, due to volumelimitations of the setup, water had to be added to the feed to obtainmore than about 90% removal. In the remaining experiments water was onlyadded to the acid and base compartments in an effort to maintain aboutconstant salt and base concentrations (simulating continuousproduction). Experiments 856-81 through 856-86 were run under aboutconstant acid (about 2.5-3 M sulfate) and base (about 2.8-3.1 Mhydroxide) to probe the effect of varying temperature and currentdensity. The final two experiments varied the control pH of the acidcompartment in an effort to mediate problems with the resulting feed pH.

TABLE 38 Summary of Results for Ammonium Sulfate Production. Sulfatecurrent efficiency (CE) reported for each of the product streams. FEEDACID SO₄ ²⁻ % SO₄ ²⁻ BASE Experiment Conditions [SO₄ ²⁻]/M CE³ REMOVAL[SO₄ ²⁻]/M CE [OH⁻]/M OH⁻ CE 856-71 150 mA/cm², 1.60-1.06 94% 61%1.00-1.26 93% 1.43-2.97 76% 60° C., no water 856-78 150 mA/cm²,1.74-0.18 84% 95% 2.69-3.37 77% 2.34-3.38 77% 60° C., water to base andfeed 856-81 150 mA/cm², 1.77-0.78 91% 80% 2.95-2.74 88% 2.97-2.79 79%60° C., water to base and acid 856-84 200 mA/cm², 1.56-0.67 80% 83%2.47-2.38 88% 2.79-3.08 83% 60° C., water to base and acid 856-86 200mA/cm², 1.67-0.63 83% 86% 2.39-2.63 88% 3.08-2.97 80% 80° C., water tobase and acid 856-88 200 mA/cm², 1.73-0.82 83% 78% 2.53-2.70 87%2.97-3.20 80% 60° C., lower acid pH 856-90 cont. 856-88 1.73-0.75 72%81% 2.70-3.72 75% 3.20-3.49 73% with new feed

Typically the sulfate current efficiency in the feed should equal thesulfate current efficiency in the acid. As shown in Table 38, there is adiscrepancy of up to about 8% in some of the experiments. While notwishing to be limited by theory, the majority of this error is likelydue to volume measurement error due to hold in the setup, for examplewhen dealing with solutions of high concentration.

FIG. 28A, FIG. 28B, FIG. 28C, FIG. 28D, FIG. 29A, FIG. 29B, FIG. 29C,FIG. 29D, FIG. 29E, FIG. 29F, FIG. 29G, FIG. 30A, FIG. 30B, FIG. 30C,FIG. 30D, FIG. 30E, FIG. 30F, FIG. 30G, FIG. 31A, FIG. 31B, FIG. 31C,FIG. 31D, FIG. 31E, FIG. 31F, FIG. 31G, FIG. 32A, FIG. 32B, FIG. 32C,FIG. 32D, FIG. 32E, FIG. 32F, FIG. 32G, FIG. 33A, FIG. 33B, FIG. 33C,FIG. 33D, FIG. 33E, FIG. 33F, FIG. 33G and FIG. 34 are plots relating tothe experiments summarized in Table 38: FIG. 28A, FIG. 28B, FIG. 28C andFIG. 28D relate to experiment 856-71; FIG. 29A, FIG. 29B, FIG. 29C, FIG.29D, FIG. 29E, FIG. 29F and FIG. 29G relate to experiment 856-78; FIG.30A, FIG. 30B, FIG. 30C, FIG. 30D, FIG. 30E, FIG. 30F and FIG. 30Grelate to experiment 856-81; FIG. 31A, FIG. 31B, FIG. 31C, FIG. 31D,FIG. 31E and FIG. 31F relate to experiment 856-84, FIG. 32A, FIG. 32B,FIG. 32C, FIG. 32D, FIG. 32E, FIG. 32E and FIG. 32G relate to experiment856-86; FIG. 33A, FIG. 33B, FIG. 33C, FIG. 33D, FIG. 33E, FIG. 33F andFIG. 33G relate to experiment 856-88; and FIG. 34 relates to experiment856-90. The following sections further discuss the results of thepresent studies and aspects of the processes.

Lithium Hydroxide Production

The process produced lithium hydroxide at hydroxide concentrations ofabout 3 M. The efficiency was fairly consistent throughout the testing,giving numbers slightly below about 80% at about 150 mA/cm², increasingto over about 80% at the higher current density. In the last experiment,the lithium hydroxide concentration was allowed to increase to about 3.5M and the current efficiency decreased by about 7%. In theseexperiments, the efficiency is predominantly hydroxide back migrationas, unlike the previous studies, the pH of the feed was always greaterthan about 7 eliminating any proton transport. However, there may alsobe some inefficiency associated with ammonium transport. As shown inFIG. 30D, the composition of the hydroxide was mostly as lithium/sodiumhydroxide with the ratio of lithium and sodium similar to that found inthe feed.

Ammonium Sulfate Production

In the majority of the experiments, the ammonium sulfate concentrationwas kept at about 2.5 to about 3 M sulfate as shown in FIG. 30E, whichprovided current efficiencies of about 90%. The loss of efficiency couldnot be accounted for by ammonium back migration. In the first experimentwhere the ammonium sulfate was at low concentration, very littleammonium was found in the feed (<about 20 mM) which accounts for lessthan about 1% of the charge. When the ammonium concentration wasincreased, the ammonium concentration increased to about 100 mM, whichis still less than about 2% of the charge. Further analysis suggeststhat the remaining charge was due to hydroxide transport from the feedto the acid. The hydroxide back migration across the N324 membranecaused the feed pH to increase. Since experiment 856-78 was run to agreater percent removal, the experiment ran for a longer period of timeat the higher hydroxide concentration, thereby decreasing the currentefficiency of sulfate across the AHA membrane. Further details of thiseffect and its consequences are discussed in the next section.

Lithium Sulfate Feed Depletion

In the majority of the experiments (except 856-78), no water was addedto the feed. Due to limitations of the setup (and time required forlarger batches), most experiments were stopped after about 80%conversion. With the amount of water transport, the lithium sulfateconcentration was still high at the end of the test as shown in FIG.30G. If no water transport had occurred, that the end sulfateconcentration would have been about 0.35 M.

FIG. 30G also shows the hydroxide concentration in the feed as afunction of the charge passed. As shown, even at the end of theexperiment, the hydroxide concentration is still increasing as hydroxideback migrates across the N324 membrane from the base. By the end of theexperiment, the hydroxide concentration was similar to the sulfateconcentration which decreased the efficiency of the process. Eventually,the amount of hydroxide leaving the feed to the acid compartment willequal the amount entering from base and the hydroxide concentration willreach a steady-state. This concentration may approach about 1 Mhydroxide concentration.

Experimental Trial at Lower Acid pH (Anolyte pH)

For example, in some experiments of the present studies, the feed pH wasallowed to increase due to the hydroxide back migration in the feed. Onecontrol method that could be used to circumvent this issue is to addsulfuric acid into the feed to maintain its pH between about 7 and 10.Since the hydroxide production efficiency is about 80%, acid equalingabout 20% of the charge would be required.

Alternatively, the pH setpoint on the acid/salt could be modified toallow for some proton back migration. In this case, if the feed pH isabove a certain measured setpoint (for example about 9.5, about 9.7 orabout 10), then the ammonia addition to the acid is stopped. The pH onthe acid drops allowing for proton back migration until the feed pHdecreases below the required setpoint. Ammonia is then added to the acidto increase the pH and the process is repeated. The above method allowsfor self-correction of the process and does not require any externalsulfuric acid. It will be appreciated that pH measurement in solutionsof high concentration salt may be inaccurate, as the sodium (andlithium) ions may, for example interfere with the measured pH. Typicallythe measured pH can be a couple of pH units different than the actualpH; typically lower in alkaline salt solutions and higher in acid. Itwill be appreciated that care must be taken to calibrate and offset forthis effect, for example when using pH as a control algorithm. Graphsshown in the present disclosure are as measured.

The last two experiments used this type of control. 856-88 started withabout 2.5 M ammonium sulfate at a pH of about 3.5 and was allowed to runwithout any further ammonia addition. As shown in FIG. 33B, thehydroxide concentration in the feed continued to increase until abouthalf way through the run, and then the concentration started to decreaseslightly. This occurred with a measured feed pH of about 10 and ameasured acid pH of about 0.5 as shown in FIG. 33C. However, there stillhad not been enough proton transport to eliminate the feed pH increase.The point at which some conversion had occurred also corresponds to thepoint where all of the sulfate in the feed had been converted tobisulfate thereby producing some free acid. As shown in FIG. 33E, theammonium concentration equaled the sulfate concentration at about 1.9mol of charge (about 2.5 M (NH₄)HSO₄).

The final experiment, 856-90, was a continuation of the previousexperiment, except that new feed solution was used. As shown in FIG. 34,the feed pH increased slightly and then stabilized before dropping to apH of about 7, while the acid pH continued to decrease. At about arecorded acid pH of −0.25, the feed pH started to decrease rapidly, andammonia addition was restarted. The acid pH increased again to a pointwhere proton back migration was limited and the feed pH started toincrease. Samples of the acid were taken just before ammonia additionwas restarted and after it was stopped. The sample before addition wasanalyzed as about 3.4 M sulfate with about 0.6 M proton (indicatingabout 3.1 M NH₄HSO₄ plus about 0.3 M H₂SO₄). After ammonia addition, thesolution was again about 3.4 M sulfate, but contained about 3.3 Mbisulfate and about 0.1 M sulfate, indicating that the free proton hadbeen neutralized.

The present tests demonstrated that it is possible to run the process inthis way. The current efficiencies for hydroxide production, feedsulfate removal and acid sulfate production (as shown in Table 38) weremore closely balanced. However, the caustic strength was slightly higherfor this run, making the overall current efficiency closer to about 73%.

The concentration of ammonium in the salt running at a measured pH ofabout zero is about half the concentration of the same sulfateconcentration solution running at a pH of about 3.5 (i.e. NH₄HSO₄instead of (NH₄)₂SO₄) which would decrease the amount of ammonium backmigration and therefore the amount of ammonium transport into the base.

Cell Voltage and Water Transport

An advantage of the ammonium sulfate system over the sulfuric acidsystem was the potentially higher current density and lower cell voltagethat could be obtained when the highly resistive Fumatech FAB membranewas removed from the process.

Table 39 shows the cell voltage ranges obtained for the current work,requiring about 6 V at about 150 mA/cm² and about 6.5 V at about 200mA/cm². In previous work, a constant cell voltage of about 7.8 V wasused to obtain an average current density of about 100 mA/cm². Thereforehigher current densities have been obtained at lower voltages. a cellwith about 2 mm solution gaps run as low as about 4.6 V at about 60° C.It will be appreciated that there is less change from the Prodcell tothe commercial cell since the feed can be run at higher conductivity.Running the cell at about 80° C. decreased the cell voltage by about 0.6V when running at about 200 mA/cm². However, this impact may be less inthe commercial cells as the main improvement is in solution conductivityand the commercial cell has smaller solution gaps.

TABLE 39 Cell Voltage Range and Water Transport Numbers. Water TransportExper- Voltage/ (mol H₂O/mol Q)⁵ iment Conditions V Feed Acid Base856-71 150 mA/cm², 60° C., no 6.4-5.5 9.3 4.4 4.7 water addition 856-78150 mA/cm², 60° C., water 5.6-6.3 10.9 4.4 6.2 addition to base and feed856-81 150 mA/cm², 60° C., water 5.9-5.8 9.6 8.8 5.9 addition to baseand acid 856-84 200 mA/cm², 60° C., water 6.8-6.4 10.7 5.9 7.5 additionto base and acid 856-86 200 mA/cm², 80° C., water 6.0-5.7 10.2 3.8 6.5addition to base and acid 856-88 200 mA/cm², 60° C., lower 6.0-6.3 9.04.6 6.3 acid pH 856-90 cont. 856-88 with new 6.5-6.8 8 2.4 7.7 feed

Water transport in this system was fairly high, averaging about 10 molof water transport per mol of charge (about 22 mol water per mol oflithium sulfate transport). This is about half the water required inorder to maintain a constant feed concentration and therefore allow thesystem to run in a completely continuous process. It may be possible toincorporate a reverse osmosis unit on the feed stream to remove theremaining water, thereby allowing full conversion of the feed. Theexperiments running at lower acid pH had lower associated watertransport. While not wishing to be limited by theory, this effect islikely due to some water transport associated with proton back migrationand lower osmotic drag into the acid. Although the sulfate concentrationwas about the same in the two solutions, there was much less ammonium inthe last two experiments.

The water transport numbers are quoted per mole of charge. Per mole ofcation in the base, these numbers need to be divided by the currentefficiency. Per mole of sulfate into the acid, these numbers need to bemultiplied by two and divided by the current efficiency.

Based on the testing performed in the present studies, the process may,for example produce ammonium sulfate at a concentration of about 3 M orhigher if lower pH control was used, produce lithium hydroxide at aconcentration of about 3 M, have an average current density of about 150mA/cm², have a current efficiency of about 80% for hydroxide production,have a cell voltage of about 4.6 V for a custom-designed cell, havewater transport from feed to base of about 8 mol water per mol cationand have water transport from feed to acid/salt of about 12 mol waterper mol sulfate or less if a lower pH on acid is used, for example.

When compared to the previous sulfuric acid process, these conditionsmay, for example decrease the required cell area for a plant producingabout 3 tonne/hour of LiOH, by over about 35%. It may also, for exampledecrease the power consumption for a commercially designed cell fromabout 8.9 kWh/kg of LiOH to about 6.4 kWh/kg of LiOH (in an about 3 Msolution). It also may, for example produce between about 8-10tonne/hour of ammonium sulfate (dry basis) depending on the feed pHcontrol regime.

Hydroxide back migration across the N324 membrane increases the pH ofthe feed. This transport may affect the overall process and differentcontrol strategies may be used to provide steady operation. Threedifferent control strategies may, for example be used:

For example sulfuric acid may be used to control the feed pH around aneutral to slightly basic pH (about 7-9). This method, for examplerequire an additional control circuit and may, for example requirepurchase of sulfuric acid. The additional sulfuric acid purchased isconverted into ammonium sulfate. Lithium hydroxide production may stillbe at about 80% current efficiency and ammonium sulfate may be betweenabout 90%-100%. An inefficiency may be ammonium back-migration acrossthe AHA. This option may be useful if, for example a suitable sulfuricacid source, and an outlet for the ammonium sulfate produced exists.

For example, no remediation may be performed and the feed pH mayincrease until the inefficiency of hydroxide across the AHA matches thatof hydroxide across the N324. This may, for example make both lithiumhydroxide and ammonium sulfate efficiencies the same. Although it may bethe easiest to implement, the stability of the anion exchange membranein high pH solution and temperature may, for example need to beconsidered. For example, a base stable anion exchange membrane may beused.

For example, variation in the pH of the ammonium sulfate may be allowedso that some proton back-migration is allowed. If the feed pH increasesthe amount of ammonia added to the acid/salt is stopped, proton isproduced at the anode until enough proton has migrated across the AHA tobring the feed pH lower, and then ammonia addition occurs again. Thismethod again matches lithium hydroxide and ammonium sulfate production,but may keep the pH at the AHA low. It also, for example has a benefitof running the acid/salt with a lower ammonium concentration. Forexample, an about 3 M sulfate solution might comprise about 0.5 Msulfuric acid with about 2.5 M ammonium bisulfate at a pH of about zero,but may comprise almost about 6 M ammonium sulfate at pH of about 4.This may, for example decrease the amount of ammonium back migration onthe AHA membrane. The acid/salt solution could then, for example be postneutralized with ammonia to produce the required about 3 M (NH₄)₂SO₄solution. Higher sulfate concentrations could also, for example be used.

While a description was made with particular reference to the specificembodiments, it will be understood that numerous modifications theretowill appear to those skilled in the art. Accordingly, the abovedescription and accompanying drawings should be taken as specificexamples and not in a limiting sense.

1-20. (canceled)
 21. A process for preparing lithium carbonate, saidprocess comprising: reacting an acidic aqueous composition comprisingLi⁺ and at least one metal ion with a base so as to obtain a pH of about4.5 to about 6.5 and thereby at least partially precipitating said atleast one metal ion under the form of at least one hydroxide so as toobtain a precipitate comprising said at least one hydroxide and anaqueous composition comprising Li⁺ and having a reduced content of saidat least one metal ion, and separating said aqueous composition fromsaid precipitate; optionally reacting said aqueous compositioncomprising Li⁺ and having said reduced content of said at least onemetal ion with another base so as to obtain a pH of about 9.5 to about11.5, and with optionally at least one metal carbonate, thereby at leastpartially precipitating at least one metal ion optionally under the formof at least one carbonate so as to obtain a precipitate optionallycomprising said at least one carbonate and an aqueous compositioncomprising Li⁺ and having a reduced content of said at least one metalion, and separating said aqueous composition from said precipitate;contacting said aqueous composition comprising Li⁺ and having a reducedcontent of said at least one metal ion with an ion exchange resin so asto at least partially remove at least one metal ion from saidcomposition, thereby obtaining an aqueous composition comprising alithium compound; submitting said aqueous composition comprising saidlithium compound to an electrodialysis or an electrolysis underconditions suitable for converting at least a portion of said lithiumcompound into lithium hydroxide; and converting said lithium hydroxideinto lithium carbonate.
 22. The process of claim 21, wherein said acidicaqueous composition comprising Li⁺ and at least one metal ion is reactedwith said base so as to obtain a pH of about 5.0 to about 6.2.
 23. Theprocess of claim 21, wherein said at least one metal ion comprised insaid acidic aqueous composition that is reacted with said base so as toobtain a pH of about 4.5 to about 6.5 is chosen from Fe²⁺, Fe³⁺ andAl³⁺.
 24. The process of claim 21, wherein said process comprisesreacting said aqueous composition comprising Li⁺ and having said reducedcontent of said at least one metal ion with said another base so as toobtain a pH of about 9.5 to about 11.5.
 25. The process of claim 21,wherein said acidic aqueous composition comprises Li⁺, said at least onemetal ion and sulfuric acid.
 26. The process of claim 21, wherein saidacidic aqueous composition comprises Li⁺, sulfuric acid and at leastthree metal ions
 27. The process of claim 21, wherein said acidicaqueous composition comprises Li⁺, sulfuric acid and at least threemetal ions chosen from the following metals: iron, aluminum, manganeseand magnesium.
 28. The process of claim 21, wherein said acidic aqueouscomposition comprises Li⁺, sulfuric acid and at least three metal ionschosen from Al³⁺, Fe²⁺, Fe³⁺, Mg²⁺, Ca²⁺, Cr²⁺, Cr³⁺, Cr⁶⁺, Zn²⁺ andMn²⁺.
 29. The process of claim 21, wherein said acidic aqueouscomposition is obtained by leaching a lithium-containing material withsulfuric acid.
 30. The process of claim 21, wherein said acid aqueouscomposition is obtained by leaching an acid roasted lithium-containingmaterial with water.
 31. The process of claim 21, wherein said acidicaqueous composition comprising Li⁺ and having said reduced content ofsaid at least one metal ion is reacted with said another base over aperiod of time sufficient for reducing the content of said at least onemetal ion in said aqueous composition below a predetermined value. 32.The process of claim 31, wherein said reaction is carried out over aperiod of time sufficient for reducing the content of Ca²⁺ below about200 mg/L.
 33. The process of claim 21, wherein said process comprisessubmitting said acidic aqueous composition comprising said lithiumcompound to said electrodialysis.
 34. The process of claim 33, whereinsaid lithium compound is lithium sulfate.
 35. The process of claim 21,wherein said process comprises submitting said acidic aqueouscomposition comprising said lithium compound to said electrolysis. 36.The process of claim 35, wherein said lithium compound is lithiumsulfate.
 37. The process of claim 21, wherein said aqueous compositioncomprising Li⁺ and at least one metal ion is reacted with said base soas to obtain a pH of about 5.0 to about 6.2.
 38. The process of claim21, wherein during said electrodialysis or electrolysis, said pH is atleast substantially maintained at a value of about 11 to about
 12. 39.The process of claim 21, wherein said electrodialysis or saidelectrolysis is carried out in a three-compartment membrane cell. 40.The process of claim 21, wherein said electrodialysis or saidelectrolysis is carried out in a two-compartment membrane cell.